P.N.
Milk supply is based on demand so if she is not nursing, you should be pumping as often as she is eating. To increase supply, pumping every 2 hrs for a couple days will help. Hand expression after pumping is also very helpful for increasing supply. Also, especially now, make sure you are drinking enough. Dehydration will cause supply to go down. If your pump is used, it may seem to be working correctly but not be stimulating the supply well enough (the motors have a year lifespan).
Kellymom (mentioned below) has a lot of good info on how to get a reluctant baby back to the breast. She is much better at it than a pump so if you can get her back to nursing effectively it will help a lot. A lot can go into this so it might be a good idea to talk to someone who can figure out what is going on. Call a LLL leader. This is the link to the Boston group page http://www.llleus.org/web/BostonMa.html.