poor thing!! I had recurrant UIT's every month for about 2 years and let me tell you, it's not fun!! what finally helped me was a doctor put me on a high dose of antibiotics for an entire month. I don't know if that would help your pup

as for wiping her when she potties, this may be too graphic for some readers but make sure you wipe towards the anus. if you wipe from the anus you could be introducing fecal bacteria into the vaginal area.
also if her PH is high that should help the bacterial problem if anything. the more acidic the urine is the less likely bacteria is to survive in the UT. that's why cranberry and vitamin c tablets help, they raise the acidity of the urine.