We've not faced this problem with deer but from what I've heard a very tall fence is the only foolproof way. Someone else told me they successfully used one of the odor type repellants but that it only worked if he saturated the area all around where he wanted protection and repeated the application every couple of weeks during summer. I don't know if that would work for your deer or not.
I've always been intrigued with the sprinkler system that senses movement that then turns on the sprinklers which is supposed to startle the deer or whatever animal intruder comes near. It may or may not work, it just sounds like a good response to give an invading deer.

Charlie