Screw buying a new LE bladder, they are expensive as hell. Unless it is a leak at a valve, you should be able to fix it.

Pull the bladder after attaching some twine to it so you can pull it back through the kite, inflate it inside your house with the TV, radio, AC, etc. off and in the dead quiet you will probably be able to hear the leak (so you don't have to submerse the bladder to find the leak). Circle the spot(s) with a Sharpie, patch it, talc the bladder, replace the bladder in the kite, make sure it is not twisted, and you are good.