I suggest taking 1000 mg of vitamin C (ascorbic acid) a day along with cranberry extract. It is acidic, and creates a hostile environment for any bacteria.
The ascorbic acid is rapidly flushed through your kidneys, and will prevent the bacteria from attaching to healthy cells in your urunary tract.
Take Cantharis — this is the most common and considered the most effective homeopathic remedy for UTI.
Barberry destroys pathogenic bacteria and strengthens immune responses, and is used extensively for kidney disease.