Does she like to retrieve, thats a simple solution Jack hates retrieving things but I taught it like a trick and if I throw something and tell him to bring it to me he will, so thats usually what I do. He enjoys swimming though, but just for the heck of it.

For the other dogs throwing little pieces of treats into the water usually works. But I use this to try and get them to go into the water, if she doesn't want to swim and is only comfortable going in to where she can touch I wouldn't force her to go past her comfort level, but thats just me.

Good luck and have fun!