1) stop with the ball for right now
2) get several good canvas retriever bumpers
3) play with the dog with the bumpers. Play tug, play catch, play chase it on a string until these bumpers are just the best thing in the world.
4) Start playing "trade" with the bumpers. Play a little big of fun tug, and then take another bumper, and entice the dog to trade with you. Big praise and reward when she does.
5) with the DOG on a longline, and the DUMMY (no, silly, the BUMPER, not you....LOL) also on a long light nylon cord, tease the dog with the bumper, and then toss it a short distance away. About 6 feet. If you have REALLY primed the dog for several days to a couple of weeks with the bumpers, she is going to DIVE on that thing. She has been DYING for you to throw it.
IMMEDIATELY show her another bumper, and move backwards AWAY from the dog (carefully now. It might be good to have someone standing by with a camera to watch you move backwards while controlling a dog and 2 longlines....i
n fact, invite ME to watch....LOL..
..seriously, be careful, and move backwards away from the dog, praising her, smiling, showing the other dummy, and encouraging. Use the longline to help her if you need to. As SOON as she gets there, go crazy. Tug tug tug play and then get her to trade.
It's a lot of fun to teach a dog like this. Once she gets the hang, you can start again with the ball, or whatever.