You'll need to decide if you 
want her to hatch out some chicks, and how you will 'manage' it.
Do you have, or can you get, some fertile eggs?
Do you have the space needed? 
She may need to be separated by wire from the rest of the flock...
..and what about all the chicks that will hatch, got space for them too once they are grown?
Do you have a plan on what to do with the inevitable (~50%)male chicks?
Rehome, butcher, keep in separate 'bachelor pad'?
If you decide to let her hatch out some fertile eggs, this is a great thread for reference and to ask questions.
It a long one but just start reading the first few pages, then browse thru some more at random.
http://www.backyardchickens.com/t/496101/broody-hen-thread
If you
 don't want her to hatch, got some ideas for that too.