1. Get her a lot more steady on land - increase greatly the time interval before the retrieve- then increase the distraction level by adding shooting, honoring other dogs, etc.
2. on land, greatly increase the denials. Throw lot more retrieves that she does not get to retrieve (you or another dog retrieves them) Give her no more than one retrieve out of 20 falls.
3. nearly all of her retrieves on land should be memory retrieves in which you walk out with her at heel, drop a dummy and heel her back to the starting point. Then turn and send her for the dummy.
3. Then go back and try the water again. Sit her (on lead), toss a dummy out 6 feet, look at your watch and wait at least three minutes, then give her a treat. If she is not interested in the treat, wait until she is. When she is calm enough to eat a treat, then give her the 6 ft retrieve.
Robert Milner
"When he stood up to speak, battalions of words issued forth from his mouth and scoured the countryside in search of an idea, and when they found one, they swiftly and thoroughly beat it to death." ---- -Anonymous