Is there a way you can move the coop? If it's not too difficult I would do that. If you can't then just get her coaxed in there tonight if you can....and close it up. She will feel safe and then hopefully come back there to roost each night. It's only a matter of time before the raccoon or whatever else finds her. I had a chicken decide to roost in the barn because she didn't like the roosters attacking her all the time....she was "roosting/sleeping" on the floor in the corner where the horses are. I shouldn't have let her do that as I knew it was dangerous and sure enough there was nothing left but feathers one morning. And she's the one I nursed back from a broken leg AND dog attack. If you can't get her coaxed into the coop this evening (maybe use bread or whatever she loves to eat), and you can't catch her to put her in there yourself, then you are left with the only option of letting her be and cross your fingers nothing happens. But like I said....something will eventually get her if she isn't locked up. There are hungry predators out there!
goodlluck!!
goodlluck!!