Poor you, I know how much you love her and it must be very frustrating.

It is in a Greyhound to run and I feel it is vital that you find a safe place for her to do so. Greyhounds can be trained and can learn safe recall but their needs must be met for them to see you and the training as more rewarding than the run that they crave.
Try local riding schools and ask if there is any chance you can use their indoor school a couple of times a week. Dog classes will have found dog friendly premises that could be suitable for a run. Local kennels may also be able to help - how about the society you got her from? Maybe they have secure runs or fields she could run in?

Good luck with her, I know it would break your heart to lose her. Let us know how you get on.