Well, the first thing is that you shouldn't be handling her until after she's feeding for you.

You need to reduce her stress as much as possible, and go over your husbandry. How is her current cage different from the one she was raised in? Are temps and humidity correct? Does she have the right size and shape for her hides? Do your best to make her current cage more closely resemble the one she's used to. Do not offer food more often than every 3 or 4 days. Do not disturb her for things other than changing water or cleaning.

Ball pythons do not feed if they don't feel secure.