If she's really ball driven, when she sees another dog, have you tried playing with the ball with her (ball on a rope would be ideal), and giving the ball to her as a reward for not focussing on the dog?
With regards to recall, have you got a long line? I'd suggest one of these if not, and just keep hold of the handle when there's a dog around and still practice your heelwork/ball work with her (totally ignore the dog if possible), but you're safe in the knowledge that she's still on a lead, so can't go anywhere