A few more tips:
Make it exciting to come to you.
Have some food or her favorite treat in hand. When she comes to you make a big deal out of it and reward her. Practice every chance you get, even if you are in the bathroom and she is 3 steps away.
Try not to say come and then go get her because she didn't.
Don't keep repeating the word , if it doesn't happen the first time let it go.
When she comes to you on her own, reward her, even if you didn't say to come.
Have you heard of clicker training? I highly recommend it, I've used it on both of mine and the "come" was the first and most important one I wanted to teach. I was somewhat amazed at the theory behind this training, and "marking" a desired behavior with just a click. Now both of mine can be running full speed away and I say "come" they stop on a dime and race back. IMHO, "come" is the most important command we can teach our little friends.
Here's a link to some info on this, maybe others who have or do use this method can chime in
I'm not associated with or promoting this site, it's just where I got my clicker and training dvd.
http://www.clickertraining.com/