Honostly go with Liz's suggestion. Or politely ask. Or go with Lor-a-ly. This is america. Lor-a-ly is more likely than the alt unless her parents are foriegn.
Why do you need to know how to pronounce her name? The only time you would conceivably need to say it out loud is when you're introducing her to someone you know... In that case just bring her over to the person and say (for example), "this is my dad" and she will then say her name out loud (to him) in return when she replies. Then you know.