I ran track but didn't jump, but one of the best and simplest ways to work on your jumping is by jumping (not trying to be a smartass!). You can do broad jumps, vertical jumps (jump and reach), squat jumps (both regular and weighted), jump-and-tucks, squat-jump-and-tucks, "skip hops", and exercises like that. Just the first things I could think of, but they work for me. Sorry if that didnt help, but I hope it does!