When they have ascites, and that is often a symptom of something else going on, cancer, infection, organ failure, then generally they just slowly deteriorate. If she's not eating or drinking, then the end may be near. If she's unresponsive, then it's probably very near. If you think she is suffering, then it may be time, and a kindness not to let her suffer. If the vet drained fluid and she felt better for a time, then draining again
may give some relief. But it also may be advanced beyond that helping. Hard for me to say. Draining is never a cure, just a temporary relief from the discomfort of the fluid. If you think it's time, then it probably is. I'm very sorry. It's never an easy decision.