What can I do, other than continuing to pay huge vet bills about my 5 year old spayed female cat who keeps getting urinary tract infections?

I have a 5 year old female cat who is spayed. 3 years ago she was urinating often, and it had traces of blood in it. She had stones in her bladder, and I spent $1000 at the vet for surgery, to get the stones removed (I had a newborn baby at the time, so needless to say this was added stress but I do what I have to as a pet owner). He recommended special food that is low in ash content, and I have been giving her the special food. He told me some cats are prone to UTI’s and stones.

This past winter (10 months ago) she had traces of blood in her urine, was urinating around the house, and I took her to the vet again, about 3 different times, for tests, and antibiotics. It was a urinary tract infection, and the problem went away. The total of those 3 visits was about $500.

Now, (October, 10 months after the last $500) she has been urinating around the house, including in the tub, and there is, again, traces of blood in her urine. Tonight she urinated on my bed. I am very frustrated and feeling overwhelmed. My sheets were just changed yesterday. Now I have to wash the mattress pad and sheets, but that is all beside the point.

I don’t want to put the cat to sleep. I have paid over $1500 within a 2½ year period on the UTI’s. Is there another solution besides big vet bills for this problem? The vet seems to consist of testing her and finding out she has an infection, and prescribing antibiotics. They probably won’t prescribe the meds without the tests, and the entire thing costs about 100–150 a pop. Repeated visits like last winter get up to $500 pretty quickly.