Best way to get her humidity and temps on track, in my opinion, is to move her into a tub.

I kept my first BP in a tank and had nothing but trouble with maintainence (sp?). Moved them into tubs and it has been spot on ever since.

You can try to add bowls of moist moss... temporary measures can be bowls of moist paper towels.

Adding moist towels to the top of your tank is often suggested.... BUT... the moment those towels dry out they will actually suck moisture from the enclosure.

You can mist and even dribble a bit of water in the enclosure, but do not soak it as you can risk scale breakdown. You do not want your snake sitting in fluids ever.

If you can post pics of your enclosure that would speed it up exponentially.

And how are you measuring your humidity? Gauge/dial hydrogemeter or a digital? And if digital, which brand... and is it an indoor/outdoor (dual reading) or a single reading.

The duals have the unit and the probe.

Bruce