tough one mate, if you've done that, you may have done too much, stop with the retreiving completely, no dummies,no balls,no rabbit. The more you do the more you will spoil, give it a few weeks then use a dead rabbit once, see how she goes with that make a huge fuss of the rabbit a lil' tease of it, then throw it out cast her off and see how she goes, don't talk to her until she has picked it up, recall and a big fuss if she completes the task.
Take it slow mate, if she does it once leave it at that with a huge fuss, then do it again the week after.Good Luck hopefully it will work out, kee