actually it's quite normal that grass gets burned from pee - it's the nitrogen content, basically the same principle as using too much fertilizer.
it seems to occur more frequently with female dogs, because they squat and pee all of the amount in one spot, rather than spreading it out more by marking, as male dogs usually do.
i would not recommend using any of those so called "miracle" cures for this problem, since it will alter the dog's urine and possibly cause harm.
your best bet is watering the grass often where she tends to pee, to dilute the nitrogen. you could keep a filled garden watering can on hand for example and water over it right after she peed, if you happen to see it.
you can also try to encourage her to drink more, it will dilute the urine somewhat, but of course then she will also have to pee more, which might just change but not solve your problem.