I took in a toy poodle that had been dumped in my neighborhood and I tried all the dog names I could think of and kept coming to Charlie and it just seemed to fit him, he was a great dog.
I was given a little blonde dog at the groomers, the owner didn't want her anymore, her name was Misty, since one of my toy poodles name was Mistyblue, I knew that wouldn't work, so I named her Honeybun and she answered to it the rest of her life.
New home new name - it all seemed to make sense to them.
Just call her the new name about 50 times a day. I didn't change the dog I got from Humane Society and she has kept up with most of her bad behavior. MIL had her first.