im sure you already know but those lamps suck up the humidity fast.

Right know i have reptile carpet and i havent had to mist on it becuase my humidity is already at 60 (i had to lower it becuz it was WAY HIGH) but it holds alot of water and maybe that will work for you better.

maybe get a fish tank air stone and put it in your water dish or try some damp sponges in the tank.

and other than misting and maybe getting a bigger water dish or making the one you have REALY FULL i really dont know what else to tell you but i hope i helped maybe just a little