One of my hens tried to go broody last fall, right after she had begun laying. I discouraged her by lifting her up off the nest and setting her down elsewhere, several times a day. I also collected eggs to make sure she couldn't start building up a clutch. It took a couple of days, but she did give up and I didn't have to go to the more drastic step of separating her from the flock and putting her in a wire cage without nesting materials. This spring I let her and her flock mates each hatch out a clutch of chicks.
When a hen sits on a nest for extended periods, she's not eating or drinking except for once a day, usually. She'll lose weight, and that's physically stressful. I weighed my hens when they finished brooding and each had lost about 30 percent of their body weight.
Winter is coming, and that's not the best time to be under weight. If I were you, I'd gently try to discourage this hen from going broody. There's no reason for it, right? You don't have fertile eggs under her, do you?
The good thing is that she'll probably want to go broody again in the spring, and you have the option of letting her hatch out a clutch then, either of your own fertile eggs or hatching eggs that you get from someone else. It's a truly amazing experience to see a hen hatch out chicks and then take care of them. I highly recommend it!