I live in a rural farming area and people dump off cats, dogs, and rabbits ALL THE TIME! Grrrrr! The last rabbit I live trapped, I started feeding him rabbit pellets and some tasty treats, like those suggested. They also LOVE oatmeal to, and it has much less sugar than apples & bananas. Use tiny pieces too. Make him/her work harder for the food. And place the trap down while you're there, not set or anything, so bun can smell it a few times and see it's no threat.
After a few times of feeding the bun, set the trap and have the foods leading to it, into it and then back past the trip plate. Be sure to set it so that it will only take a slight touch from the bun to trip it closed. I've had to walk up and close the trap myself sooo many times because I didn't have it set right. Takes some finesse, that's for sure! But, this sounds like a big bunny, so it should trip the trap easily. Trick is to have them stop on the plate to eat the foods. Then they trip it every time!
Good Luck!