Stuck at 1350, any advice to reach 1500 (Rapid - 10/20 min)?

I recently hit 1350 points after being in the 1100 range for a long time. I just changed my style of play without studying anything in particular but now I'm stuck in this range (the new one, 1350) again. What does it take to get to 1500 or 1600?

Analyse your lost games so as to learn from your mistakes.

If you stuck by doing nothing and not studying, maybe try studying? While I won't comment on What to study (how much puzzles, how much lessons, how much and which books you should read), I will say that the How can be pretty universal and generic: practice deliberately and actively. Which means that instead of just playing many games, looking through them "a bit" and then just going on with your day you should spend more time reviewing (maybe playing fewer games) your mistakes, writing them down, try to spot them or similar mistakes in your next game and avoid them. The simple Do->Review->Improve->Do loop. Don't try repeat what you are already good at, instead repeat parts which are hard for you. Daily! And do try to slowly increase studying time instead of going all out in the first week(s) just to drop it in a month's time.

And of course, puzzles and lessons are good to actually have a clue what to do and be able to spot what's going on but there are tons of information on this site and from better user on which one are good for you.