How can I get my leaps higher?

just practice every day till you get it right.

just practise every day that is all you can do. jumping on the trampoline will not help you if any thing it will make it worse because if you keep jumping on the trampoline well then it trains your mind that you dont need much effort you need to train your mind to rely on your strength.to get stronger do some sit ups and get you abs working.

hope i helped

I dont believe a trampoline can help you mostly because it cannot help you develop the muscles you need for jumps. practice and streach is really all we can tell you. it might help to excerise streangthen your arms more to help you push off the floor with you legs-that you excerise streangthen and streatch already. not only will this help you with leaps, but also turns. funny enough this can also help with posture.makes your jumps just 2 seconds longer and a few inches higher in the air than everyone elses. it does happen =D
maybe soon, while practicing youll get that epiphany that

leaps are very much about timing and your plie. it really is all about physics and getting your legs to hit the correct point to get you up higher. plie is very key, i have short Achilles tendons and that restricts my plie which restricted my leaps. it really takes practice and figuring out what works for your body. when you hit the correct mix of position and timing, trust me you will feel it. leaps will become easier and easier.
stretch your hamstrings, quads and calves to get your plie deeper and practice practice practice to get your form and timing correct.
i dont recommend the trampoline unless it is used for strength training