Just to offer a different perspective: First, were there any other changes when her behavior changed, such as changes in the weather? Even if the conditions in her cage are controlled, ball pythons are highly attuned to differences and changes in temperature. If the temperature of the room changes, the temperature gradient in her cage will also change even if the exact spots you measure and control with a thermostat stay the same. For example, the corners farther from the heat source will change even if the area under the heat source hasn't. Given her age and size, it's at least conceivable that she's hitting sexual maturity and changes in the weather have cued her to start looking for a gentleman caller. In which case, she'll probably settle back down again after awhile, probably when the weather changes again.

As to whether to increase either her prey size or her meal frequency, you should definitely weigh her and monitor her body condition. If you aren't going to breed her and she isn't skinny and isn't growing much anymore, she does not need more food even if she is of a different opinion. Breeding involves a substantial metabolic cost, so females that will breed need to bulk up more. But don't feed an animal that isn't going to breed the same as a breeder feeds one that is. It's like eating like you're pregnant when you're not. An awful lot of ball pythons are overweight tub potatoes, and that's not a recipe for long term health.

Another possibility though - if she's eating a lot, always hungry, and not gaining weight, she could have some sort of internal parasite that's essentially stealing her dinner. That could conceivably have come in on her prey at some point, especially if she eats live. So it might be worth sending a fecal sample to a vet just to be sure.

You could think about getting her a bigger cage. A 40 gallon tank is really not that much space for an adult BP, especially a larger one. They really will use and benefit from larger enclosures, as long as the enclosure has lots of hides, cover, branches, tubes, and other "clutter". In other words, a giant tank with one hide and a water bowl won't help, but a large space with lots of place to go, hides at different temperatures, things to climb, ways to get around without being seen much, etc, will give her something to do besides just climbing the walls.