First take her to the vet to make sure there is nothing physically wrong with her.
Second you need to clean the spots she's going. The smell must be GONE. Without that she won't stop.
Third more litter boxes, put them at every entry way, every window, and wherever she has gone before.(even if it's on counters) Once there is no more spraying, you can slowly reduce the amount of litter boxes. But if she sprays you must put them back. It's a slow process.
Fourth it could be territorial marking, if you live in an apt there isn't much you can do about the territory. But if you have a yard nearby which is what I'm going to assume. You should look to see if there are any spots other animals are using as a potty around your house.(you may have to look in flower beds/loose dirt) If it's found you must clean that up also. Once it's clean either make it un-potty-friendly or go to the pet store and get one of the humane deterrents.
Fifth exercise your cat. A cat is just like a dog. When they're panting and laying down. They're tired. But just like a dog you may have to get them to this state multiple times a day.
But if you do decide to give her up, don't get another animal.