What are some stretches and excercises to help improve leaps? (Center and Split)?
 

I can sit in both my right and left splits with no problem, and I am 2 or 3 inches away from my middle splits, but I can't seem to get any height when I do my leaps, no matter how hard I plie.

the things that will help you out with that a lot are: Jump Rope, Sprinting, this one might help you the most, climb a flight of stairs on your toes, and using only your tippy toes. remember to stretch before these workouts as they can be pretty tense on your legs.
also i kno a practice a lot of basketball players do is they will walk around on thier tippy toes, or stand on like the curb with your heel off the curb and you toes (front of the foot) firmly on the sidewalk, and then raise and lower your body with just using your leg muscles(the lower muscles) in your legs.