C.W.
I hope that this has been going on so long that she isn't actually wetting the bed anymore, but rather is wearing a Depends or other type of product. Our daughter wore pull-ups until she was 7. We let her know that her body would figure it out, probably before she was 21, and that it didn't bother us at all. We would buy the pull-ups and put them in her drawer so she could empower herself to keep the bed dry. She did eventually start waking up when she needed to use the bathroom.
If you want to try some other simple suggestions you could offer up limiting liquids 2 hours before bedtime and setting an alarm for the middle of the night to awaken her in order to use the bathroom, instead of sleeping through the event.
Depending upon how the girl is handling the issue (meaning if it is really bothering her and impacting her self esteem negatively) perhap some counseling would be in order.
Good luck.