How to keep humidity up?

[Surrealasm]

I've got an exo-terra small vivarium for my Amazon Milk Frog (He's still very small). I've laid a pane of glass over the top screen-vent area so it covers 3/4 of it, and there's a heat lamp setting on top of that. Additionally I've got LECA that's usually pretty moist with a heat pad underneath that, in an attempt to coax out more humidity.

Despite all this, I still have to spray 3 times a day, and when I come home from work in the evenings, the hygrometer reads that it's gone from just above 70% to 50%.

Any tips on how to get better humidity retention?

[geckolord1]

set up small fountain or fogger maybe that'll help

[Enfinite5]

I would defiantly go with a fogger something like this DIY fogger for under $30