Hi. I've played La Campenella and in fact, I'm playing it in Ancona, Italy this summer so it's very fresh in my mind.
Try "dotted rythem" practice for those leaps. If you aren't familiar with that, it's a technique of playing only certain sections faster (usually, just the exact point that you are unable to play fast). so if you have a hard timd going from the D# to the next octave D#, you would start with your 1st finger prepared over the lower D#, and then when you're mentally ready, you play the lower D# and then as quickly as posible, get off that note and try to get to the higher D#. Doing it that way allows you to play very fast in a section that normally you'd have trouble playing. With specific practice right on that spot, you will soon be able to handle those leaps with no problem. Doing it that way has made them like 2nd nature to me now. See how it goes.
Rich