How I would handle this...it's going to take some work.
So, first is to tire the dog out. Long walk, play session, whatever...you want her relaxed and tired. A tired dog is a good dog! Do this daily, if you're not already.
Then, don't let the dog and cat around each other unsupervised. Even if this means relegating the cat to the spare bedroom or whatever for awhile. The important thing is that you don't let your dog practice the unwanted behavior towards the cat. Chasing is self-reinforcing, so the more she goes nuts, the more she's going to want to. Keep them separated.
So then you have a tired dog, and a cat confined into a shut-off room. Okay. Put the dog on a leash and do obedience work with her. During this, let the cat out. You should be keeping the dog's focus on you and rewarding her for that. Correct her if she goes after the cat, but your goal should be to keep her paying attention to you and keep it positive. She'll know the cat is there.
Do that for a bit, then progress to letting the dog be on a leash but not actively working, and the cat out. Again, correct her if she goes after the cat, but just as importantly, reward her for ignoring the cat.
She needs to know what you want, not just what you don't want. Gradually extend the time. Eventually you can remove the leash.
It sounds like a lot of work, because it is. But, I've introduced a lot of dogs with a high prey drive to cats and that's what works for me.