Okay, if you know it's dehydration then hydrate like crazy. When I was in your position, I kept a dropper bottle of water on top of the screen. Every time I saw my chameleon get near a side of the cage I went up and started pushing water through the screen. Lots of good drinking happened that way. Wax worms are also good for hydration (I suspect any "maggot" worm is a good choice).