Just play lots of Insanes. Practically all of them have jumps to some degree. By diversifying instead of restricting yourself to a regimen of a few select songs, you'll learn to play jumps of all sorts of spacing, rhythm, and BPM. You may not feel yourself getting better, but believe me, you are. My most significant skill increases were over periods I thought I was banging my head on a brick wall. Eventually, you'll find yourself naturally hitting things you consciously feel should be too hard for you.
Basically, don't consciously think about getting better, and just play stuff that's both challenging and fun for you. That's the only way to get better at this game.
