It might be worth encouraging her to take her morning/evening promenade on hardstanding or some bare ground while being on the lead.
Yes, I appreciate this isn't really convenient, but it at least saves your lawn and negates the need for any dietary additions.
We are currently training a Guide Dog puppy and we've been told that we should train the dog to make motions on command on a piece of hardstanding. It's worked so well that we're going to do the same thing with any future dogs we have.
It might be an idea to ask your vet for advice on this as well (you're paying for treatment, so you may as get free advice while you're there).
According to this article, dogs urine isn't acid, it's just really high in nitrogen.
Solutions:
Water your lawn: The best way to reduce the damage to your lawn is to dilute the urine by saturating the spot with water immediately. By the way, this approach also works should you accidentally spill fertilizer on your yard, too.
Water your dog: Make sure your dog is well hydrated to dilute the strength of the urine. Adding some canned dog food, or moistening dry food with a little water, is another way to add water to their diet. Many dietary additives make your dog thirstier (usually by adding salt), leading to more water consumption. So there is no real magic there.
Examine diet: Consult your vet to see if you are feeding your dog the right amount of protein. The nitrogen in urine comes from protein metabolism, and some dogs might benefit from a lower-protein diet. This is not something that should be undertaken without a vet’s analysis of your dog’s diet and lifestyle.
Buy high-quality dog food: In general, higher-quality dog foods have higher-quality protein sources, which are more easily digestible and less likely to leave by-products in the urine.
Train your dog: Train your dog to go in a designated space away from the main lawn. While this may sound like a daunting task, dogs really can be trained to go in specific places on command. Make sure the area has mulch or pea gravel that is easy to replace and keep clean.
Plant resistant grasses: Fescues and ryegrass are more resistant to urine burns than grasses like Kentucky bluegrass and Bermuda.
Keep your lawn healthy: A healthy, well cared for lawn can withstand the occasional overdose of nitrogen better than a stressed lawn.
Choose supplements carefully: Your local pet store likely has a variety of products claiming to bind and neutralize urine. Results are not proven on these products, and you should consult your vet to make sure they are safe before using. Generally, I feel it’s better to use solutions that work with biology and nature, rather than trying to alter it.
Obviously, consult with your vet