Its not uncommon for ball pythons to go off feed !
I have a female that will go off feed for 2-3 months every year.
I have found that small meals on a regular weekly schedule helps. Let her weight be the deciding factor. If she is 1000 grams I wouldnt get concerned unless she loses over 200 grams. Breeder females will lose up to 50% of their weight when eggs are laid.