I would try to cut it down. Granted 'long-term' takes on different scales in a situation like this, but if you can keep her comfy on a lower dose, it's so much easier on the body and also cuts down on the side effects--like increased urination. You can always up it again later if you need to, but finding the minimum effective dose with harsh meds like steroids is always a good idea, imo.
"We are--each of us--dying; it's how we live in the meantime that makes the difference."
"It's not what you gather, but what you scatter that tells what kind of life you have lived!"
"Be kinder than necessary, for everyone you meet is fighting some kind of battle."