The only thing I did to Wyatt was shave his ears and they are both up, he is 5 months old. The top part of the left one sometimes will flop down. I have read on here that sometimes while they are teething their ears will go down and that they come back up when they are through teething.
Here is a link to a couple of pictures that I just posted of Wyatt. His are up right now. Last night his left one had flopped over some.
I never taped his I just shaved them. I would think that since they were up when you got your puppy that chances are good that they will go back up. Of course I'm not sure and this is only my opinion.
http://www.yorkietalk.com/forums/showthread.php?t=28010