You could mist more often or using a humidifier near the cage. I use a ultra sonic humidifier to keep the humidity up in my chameleon room. If you go the humidifier route just be sure to clean and disinfect it regularly.
I have a humidifier from Walgreens. One that the vapor comes from just one 1 1/2" hole. Went to lowes and got 3, of clear tubing, 3' of PVC and some elobows and made a homemade fogger. Workings great.
I have 2 Jackson's and they require 70% hunidity.
Can even have the one fogger humidify mutipule enclosures.