Sorry to hear about your pup. If your pup is getting UTIs frequently, then the infection was never treated completely.

When she is done with her meds, take another urinary sample and have the vet reanalyse it. If there are any crystals or even the slightest sign of infection, continue with the meds for another cycle.

Jazz had one when we adopted her. We did her meds accordingly, then the vet said the infection should be gone. Were we wrong. About 2 months later she got another. This time I took her to another vet my friend recommended, and sure enough, we had not treated the initial infection completely. We did another cycle of meds, did another test (some slight cell count still high) then another cycle of meds. The last urinary test we did on her, was perfectly clean. We have not had a UTI since.