Advice/opionions, please, on cleaning schedule/method for terrarium.

[KimW]

I have a 12x12x18 terrarium and 1 WTF. I have had him for almost three years, but having gone through an illness, I am reviewing my care routines to ensure his continued good health. I have not keep a specific cleaning routine/schedule and I feel this is most likely the contributing factor in him becoming ill. His set up is as follows:

Artificial jungle vine (the flexible kind, twisted into braid like thing)
assorted other artificial plants/vines
Plastic " shallow reptile pool"
coco fiber substrate
planted living patches of frog moss (these are firmly rooted, and don't break up easily and my guy is tong fed)
I am very good about rinsing and changing his water daily, as well as inspecting for and removing any fecal matter.

How often should I clean the whole terrarium? In the past I have done it about every three months, however, I think I may have let it go longer and perhaps that is why my frog became ill. What is the ideal cleaning schedule for this type of set up?
My cleaning method consists of removing everything from the tank and rinsing it (the terrarium) well. Then I spray it with Zoo Med "wipe out" (and follow instructions on label). I rinse plants and bowl with boiling water. Let everything dry in the sun, then replace with fresh substrate.
Can anybody add/suggest anything that I am not doing, or could do better, as well as how often?

**opinions - sorry for any other typos