Try learning something that is over your current skill level.

Had the same problem. So I decided to try something new on acoustic guitar, Figer tapping/acoustic percussion, like Andy Mckee. I'm learning drifting. It's pretty cool and amazing in front of people because they don't see that ofter. You can also try : Rylyn,from Andy.

It isn't hard, it isn't easy. Just takes time, but the result is amazing, that was my way to improve. I hope it helps, you'll always find something harder, just never give up!

Try playing a whole new genre of music, even if it's something you hate, it's good to have those skills.