Stuck at 1300-1400 ELO

I'm pretty stuck at this Elo rating, and I really believe I can move up. I've reviewed my games, and I find that most of them have good move performance, and the games I tend to lose are due to poor exchanges of active pieces.
What advice would you give to someone who is stuck? How do you cover endgames?
What is the usual difference between 1400 and 1700 Elo in terms of game quality?