Whether you get fertile eggs for her to sit on or just let her sit on nothing for 3 weeks or so, I would advise putting her off the nest once or twice a day to enourage her to eat, drink, and poop. Many hens who turn broody don't take care of themselves. If you're not wanting her to hatch chicks, then you can try to break her from her broodiness. Do a search on "breaking a broody."
