His first Christmas here, my cat ended up in the vet emergency with a UTI. This and the previous UTI he had about a month or two before cost us well over a thousand pounds (we put off getting pet insurance when we moved here). At first, we used the vet prescribed Hills, but the dry made him ill (vomiting and loose bowels) and the wet was too expensive and he still vomited a bit with that.
What we've done, and this has prevented a flare (over a year) so far (touch wood) was:
1)Weight loss. He's still chunky, but he's taken off a bit of weight.
2)Switched to mostly wet diet. We were using Sheba for a while, but now we're feeding him the Purina pouch food (I think it's Gold or Pearl or something). I know a lot of cats who are used to dry food will refuse wet food for a while. Mine is addicted (and yes, I use that term purposefully) to dry food. It's like candy to cats. They are obligate carnivores and most dry food (and some wet) are really aimed at vegetable centred omnivore diets. Cats do no need the sugar (starch), and do not do well with it. We thought he'd never get used to eating wet, and it took a couple days of him totally turning his nose up at wet until he got hungry enough.
If you must stick with dry, I'd suggest adding water to it. Enough to add some moisture, but not enough to totally make it soggy.
Because I followed the advice of American commercials and tv vets on what to feed my cats (Oh, he must need the rice and stuff!) he has obesity problems, pica, and got ill with UTI.
If you can find a regular supply, Encore or Hilife are extremely good foods. Unfortunately, the supply is sketchy here, and I don't like to switch foods on him all the time. These two foods are mostly meat. You could also look into BARF (biologically appropriate raw food). We may turn to that if he gets ill again.
With a mostly wet diet that is meat heavy/exclusive, your cat will have fewer problems with blood sugar and you will be ensuring he or she is taking in a lot of moisture.
It takes a lot to get used to for both you and your cat. We usually feed our cat two pouches of wet a day and then a small snack of dry at night. I really wish I hadn't added the dry as he has started to get a bit mental again, obsessive about food, and chewing things. This is with more food, not less. I was concerned that he was losing too much weight, but now I am considering just giving him 3 pouches of wet a day.
3)Reduce stress/use Feliway
4)Exercise him or her regularly, especially if he or she is an indoor cat.
If you can afford Hills or specialist diet food and your cat tolerates it well, great. We found very good results upping his moisture, lowering his starch intake, increasing his exercise, reducing his stress, and lowering his weight.
No matter what you choose, good luck.
ETA: The high meat food I was talking about:
http://www.hilifepet.co.uk/osb/showitem.cfm/category/1http://www.encorecatfood.co.uk/index.html