Hey Frogger!
Hmm well.. If you knew the wattage that would be helpful. Usually Tree Frogs shouldn't have more then 60 watts. Also, is your thermometer under the light or on the other side? Usually for me, the more I mist the cage or use my fogger, the temp goes down. Also, there are some timers you could buy that shut off the lights every hour or so, that might be helpful. I did see this one device that controls humidity and temperature. It's like a sensor and when it gets too hot or cold it adjusts the heat source. (Same with the humidity.) But I'm not sure it works with lights or if it works with like heat pads... Anyways sorry I wasn't too much of help!!
-Good luck!
~Lauryn