I don't have much to add in term of what to take via supplementation as everyone has covered most of that already. In fact depending on what type of damage is done will depend on whether it can be fixed as well. For instance, in laymens terms, once the filters are blown out by high BP; they aren't going to repair themselves and the key is prevent further damage(by keeping blood pressure under control).
Also, I don't know what her creatinine values were prior to recently, but if there was a recent decline, it could be from the UTI.
One more thing, I recently started using a product called "Kidney Support" from Herbalist & Alchemist. It comes in liquid form and is pricey. My creatinine had been running around 2.4 for the past 2 years(transplant) and had gone up quickly to 3.0 about 10 weeks ago. The next labs I had was about 4 weeks ago and it was down to 2.0. However, I don't know that it had anything to do with the supplement necessary because we also switched anti-rejection meds over this time period to a medication that is much less kidney toxic.