Cheer Tryouts In Less Than 2 Weeks.?

I can do a forward roll, cartwheel and roundoff both standard and one-handed. I'm about to start working on my handstands and the front walkover. But my jumps are terrible, how do you get more air? Is a herkie, hurdle, pike super important if you can tumble pretty well? I'm a freshman trying out for my sopre year starting in the fall. I want to atleast make JV, not varsity or anything. Any diet or workout tips? Please and thank you (: