It's probably not an universal thing, as every musician/producer is an individual, but for me what works the best is having these little projects, kinda like a game, where I set myself a time limit and a specific goal. If I just mess about with synths, samplers and drum machines I'm more or less just repeating the same old mistakes, with almost zero progress.
As an example, earlier this year I had a goal which stated that I must learn the skills involved with the production of house music and the end goal was for my favorite house musician/DJ play my track on his DJ gig here in Finland. I worked my ass off for that to happen and it actually happened too. Had I spent those 4 months just making what are basically just simple variations of my old tracks I would've never progressed as much as I did.
Currently my project is to make a g-funk influenced hip hop EP which must come by the end of August 2017 and since I started the project, I've been making beats, writing lyrics, learning how to rap, listening to all kinds of hip hop music to steal their tricks and studied the subject by reading and watching tutorials like 10 hours a day.
It might not work for you, but maybe take it into consideration. Set a goal, set a time limit, then work hard to reach that goal in that time.
IMO, once you've learned the basics of production, it's EXTREMELY easy to stagnate, basically make hundreds of beats/tracks/songs that are all more or less the same. Once you're past the rookie stage, you have to start taking things seriosly if you want to progress.
Sports ain't music, but it's still kinda like doing pushups. If you want to make a 100 pushups, you have to work on it, consciously try to improve and set the bar higher every day, doing 20 pushups a day just won't get you there.