The name you choose doesn't have to sound like Lulu at all actually. Really, all a name is to a dog is something we say to get their attention. I'm sure she'd will catch on pretty quickly to a new name just as long as you praise her whenever you say her new name and she looks at you in response, also remember to say it as often as possible when you're talking to her. A friend of my mom's just got a 5 year old dog from the Humane Society and they changed his name with no problems at all, it only took him a couple weeks to learn it...

Anyway, she is very pretty! Good luck