Should I abandon everything I know and learn a new opening?

I've been 1600 rating for a long time and I'm sick of it. I want to cross the 1800 barrier but I've shown zero signs of improvement over the past 5 years and it's really disheartening.

As white, my openings are: king's gambit (against e5), grand prix attack (against sicilian), exchange variation (against caro-kann) and advance variation (against French).

As black, my openings are: caro-kann defence (against e4) and old benoni (against d4).

Despite playing the same openings for years, I still haven't mastered them. I still don't know all the lines. I've been lazy and haven't bothered to learn them properly. So that leaves me with 2 options if I want to improve:

1) Learn the lines properly. Master these openings.

2) Abandon these openings altogether and learn something more solid.

Which approach should I go with?

A solid opening repertoire definitely helps, but you're talking as if that's the only way to improve.

IMO the 5 basic areas are:
Openings, strategy, tactics, endgame, and annotated game collection.

My usual advice for improvement is to pick your weakest area and study it. For the vast majority of players their weakest area is not openings.

I think your openings are fine except the old benoni. Don't play that, you're just giving yourself headaches, especially if you don't know a lot of theory. You'll get better positions playing a queen's gambit declined knowing next to nothing than you will a benoni knowing next to nothing.

Since you're 1600, I'd say you're pretty darn good at not blundering material to simple tactics. IMO usually the next step is strategy and endgames. I recommend Pachman's Modern Chess Strategy or Soltis' Pawn Structure Chess. For Endgames I very much like Dvoretsky's Endgame Manual. Yes even for 1600 because that's when I read it, but I understand others will disagree with me, and even recommend Kmoch's Pawn Power in Chess instead of Soltis. Their recommendations are fine too. This is just my two cents. Read book reviews and choose for yourself.

One can see a Pachman sample at:

http://store.doverpublications.com/0486202909.html

Trash the King's Gambit.  You should be ok with the rest if you put the work into it.

Pawn Structure Chess by GM Andrew Soltis (2013)

https://web.archive.org/web/20140708101523/http://www.chesscafe.com/text/review908.pdf

In a previous discussion, someone reported a passage from Pawn Power in Chess by Kmoch: "The lengthening of the rearspan is often favorable, inasmuch as the expansion of territory behind the pawn increases the freedom of the pieces. By the same token, the shortening of the frontspan limits the freedom of the opposing pieces."
I'm not exactly a big fan of that sort of writing, but there nevertheless seems to be a widespread opinion that the Kmoch book is worthwhile.
"... [Pawn Power in Chess] should be on everyone's list [of favourites]. ..." - GM Nigel Davies (2010)
Another point of view:
"... Hans Kmoch’s Pawn Power in Chess is considered a classic by many. Nonetheless, most people found it daunting and confusing, given its weird terminology. Also the scope of the book was more theoretical than practical; not an easy book to read and study with. ... must be frustrating to read and study from for those rated below 1700. ..." - Stephen Ham (2000)
https://web.archive.org/web/20140708110136/http://www.chesscafe.com/text/review249.pdf

One can see a sample at:

http://store.doverpublications.com/0486264866.html

"... before discussing the specifics of Dvoretsky's Endgame Manual [henceforth 'DEM'], a word of warning is in order. I must emphasize that this is a terribly advanced work that I don't think is a very good way for the average player to study the endgame. The majority of the examples are complex and position-specific, and neither the average student nor even strong masters will follow or play over most of the hundreds of positions that are given extensive analysis, not to mention the subvariations derived from those positions. Even when introducing 'the basics', Dvoretsky's approach is often more complex than is necessary for an average student, and in any case such a thick book will seldom be used for the sake of elementary instruction. The majority of the other material is frankly very difficult. So take note: I don't want to be blamed, in praising this book, for your purchasing something that you find intimidating, relatively dull, or otherwise unsatisfying. That said, if you are up to a real challenge and have a great deal of time to devote to reading and playing over examples you will inevitably derive great value from this work. ..." - IM John Watson (2005)

http://theweekinchess.com/john-watson-reviews/the-end-game-comes-before-we-know-it

http://www.jeremysilman.com/shop/pc/Dvoretskys-Endgame-Manual-3rd-Edition-78p3502.htm

https://web.archive.org/web/20140708233815/http://www.chesscafe.com/text/review399.pdf

https://www.newinchess.com/media/wysiwyg/product_pdf/2703.pdf

u want to improve but u say u are lazy.

U could change your openings, it wouldn't make any difference : it would even be a loss of time.

U just have to know more what u play.

Sorry but chess is not easy and requires working.

I said I've been lazy in the past... I never said I intend to be lazy in the present and the future. I'm willing to put in the work.

Keep on improving your tactical skills. The purpose of studying openings is attain at least a playable middle game. Changing and learning new openings waste time. Online tactics exercises are not that great. Get an excellent tactics book like Encyclopedias of Chess Combination or Great Book of Chess Combination.

I don't know enough about you to say for certain which approach will be best for you. But my feeling is that you should make some changes to your repertoire. It's just a good way to learn about some different positions and grow as a player. Don't try to change everything at once though, or you may feel a bit overwhelmed!

Start with one change in your repertoire, so that you can learn the new line really well (playing it, analyzing the games, looking at GM games, checking the theory, understanding the positions in general). I'd probably replace either the King's Gambit (maybe with some version of the Italian Game, e.g. Scotch Gambit style with a quick d4?) or the Old Benoni (maybe Slav?) first, then work from there.  

I'm surprised people have singled out the King's Gambit as bad without mentioning the old benoni. Sure I don't recommend the KG, but still.

My feeling is if you're well prepared in the King's Gambit as white, then the engine may not like your position, but you'll have practical compensation. If you're well prepared in the old Benoni you're rewarded with a middlegame where dozens of moves of grim defense might earn you a draw.

The problem is not openings here.

Althought I don't understand old Benoni's choice.

Try to play simple.

KG is not a bad choice, at least u know what u have to do.

Old Benoni is more complicated and needs experience and some skills to be played properly.

Scotch gambit as proposed above is a good idea.

The idea at your level is to play with initiative : so KG, scotch gambit, Evans gambit, are all good stuffs.

With black it is more complicated, but stay "simple" as I said : really, 1.e4 e5 and 1.d4 d5 are often advocated, for good reasons...

I agree that openings is very rarely what's useful to work on.

But maybe we can make it more fun

I was once given some good advice along the lines of get Bronstein's Zurich 1953 book and play over every game, and this will help train you how to play the Nimzo Indian. But to start learning the Nimzo, first play over all of these games.

I would add that when someone is making a change in their opening and unsure what to change to it can be quite helpful to look at the opening and middlegame diagrams in books on various openings, if you like what you see in a book's diagrams and its reputation is not too bad then go for it. If you don't like what you see then don't play it.  Another factor to include when deciding is how good a job the author does in explaining things and whether the author included more analysis than you wanted or not enough analysis to you. If you don't have the paper books to look at when deciding you can seek  previews of books' diagrams on the internet and search for more diagrams on web pages, look at the amount of analysis, and amount of explanations, plus reviews might be helpful. 

somewhere is a link for 34 moves about that mate, explanations with triangles.

(dont remember where but also it is on lessons)

the main things (at least for me) is to avoid blunders. the rest of theory its impossible to apply doing mistakes/blunders.

You play nothing but bullet, and blitz.

And you think openings are are why you're not improving.

Ponder that for awhile.

Openings aren't your problem.

I took a look at your game history to see if I could notice a pattern in why you lost your slower games - and then I noticed that you didn't have any slower games. You haven't played a "rapid" game in the last year. 

So if you want to improve, play slower games. Work on your tactics (you lose a ten-minute game in your history to a simple double attack in the opening). Work on your endings. Learn to see deeper into positions. 

Your problem is not your opening choice. 

The way to learn about what springs out of the original position is to look at the Giuoco with c3 and d4, not d3, and observe particularly what happens when Black plays imprecisely. Look at related openings. The King's Gambit is highly sophisticated you need to build up to that. I am bored to tears by the Queen's Gambit but how it unfolds is key to the closed and Indian openings. 

Someone pointed out there's no solution to lack of due diligence. Learning needful new things is also (like plain work) so fundamental to human life that to see doing so as "abandoning everything you know" is very unpromising, as an attitude.

If, like me, you aren't particularly good at chess then play it for fun (no matter how much more you study you will still be in a class it will just have another number or name) and most importantly, find out what you really love and are good at and invest your time learning everything about that... is one way to look at it.

Just try to study the openings you are familiar with already, and also try to study some strategy, tactics, and how to keep active play in the game.  Your problem might not only be that you don't study enough, it might be that people at your level usually train, and study too, it is not as easy to beat them as when you were playing at a lower level.  The higher your rating the tougher the game becomes.