How do you determine when it is appropriate to transition a patient back to peritoneal dialysis after they were switched to hemodialysis due to PD catheter removal for refractory peritonitis, once the infection has been treated?

I am not aware of any data/evidence to guide this. I generally wait for two weeks after the completion of treatment to be sure that the infection has indeed been eradicated. I think it's OK to try PD catheter placement at any time after that.