How to improve at chess

Recently (within the last year) I've lowered the amount of turn based games I play on chess.com, and also the amount of games I play against my chess buddy I live with. Since then, I've seen my rating Over the Board (OTB) increase by around 200 points in one year. Since 01/01/15 it has increased again another 26 points with 3 straight wins. But here's the thing:

I have no idea what caused it...

I feel as though my chess is a lot better now than it ever has been. But I don't study chess like I used to, my main chess activities are playing live chess, the occassional OTB tournament and playing OTB matches for my club - all of which I used to do just as frequently. At the start of the last 5 years:

Year = rating

2009 = 1514

2010 = 1600

2011 = 1620

2012 = 1620

2013 = 1620

2014 = 1650

2015 = 1827 (latest)

A side question:

How do I get better from here? Last year I thought my lifetime peak was going to be 2000 but now I can see it going higher than that.

:)

If you like we can play two 10 min time control games and then I'll tell you what you shall improve...  

Sounds good to me. Whenever you're ready!

Well, we've played two games and I've seen your today's games. As a coach with some experience I can tell you that you need:

1. To solve much more puzzles in Tactics Trainer. 
2. To learn theoretical lines in 1.g3. and in 1.e4 g6 and 1.d4 g6 (those are minimum). 
3. To think about ratings and titles less. Play chess and play it as good as you can or go have rest and then play as good as you can. 
4. To watch more chess videos. Every idea from a video about openings must be tested in blitz games.
5. To choose an engine to play with (rated 2300 or even less, set it your level) or play real OTB long games with someone. Only 25 min games and longer are really effective for developing of positional play.    
6. To analyse every of your lost games (especially long time ones) with engine to understand when you've made a crucial mistake.  

play

It's not about becoming stronger, it's about getting rid of the weaknesses in your game. Each loss will help you expose where your weakness lies and will give you direction on what to study next.

Thank you Cothurnatus. However, you didn't see my full strength today. I will play you again another time! 

Thanks yes_dear and cornbeefhashvili

Now,just after our 10+ games match, I see that you've improved your play greatly. Hope, you've used some of my tips to do it. Good luck! Always glad to chat and play with you, my dear friend!  

What you saw during our long games was not my full strength. I think I had a bad day for chess! Today, my bullet was very good, and so was yours. It was fun :) 

Try to play on FIDE Arena - http://arena.myfide.net/. I've got Grand Master's title there this year and it is totally official (I play 3 min games mostly ). I think you can be an Arena FIDE International Master if you play there. 

GM Arena title requires 50 games at 2000+ in rapid or blitz category, is that correct ?

Yes. That is correct. I play better and less there. So I have 2100+ in Blitz there. And one can have the norm having 2000 in 100 blitz games or in 150 bullet games there also.