I just take my broodies that aren't on eggs, off the nest a couple of times a day, when I'm out there. I take them over to the outdoor water in the yard or the dustbath out in the yard. It gets them out of the coop, gets them some exercise and it's a nice diversion. I also take them over to the food at times. They usually give up after awhile. I've found that a lot of my chickens were the broodiest the first couple of years and then, not as much.
As long as the coop has enough ventilation so that it's not hotter inside than it is outside, it shouldn't be hard on her to be in the coop. If she eats and drinks every day, she should do fine, until she gives up. Even though I keep a little bowl of food and water next to broody chickens, I still take them off the nest a couple of times a day, to encourage them to give up and go enjoy life, when they aren't on eggs.
If your coop is really hot, you could always set up an area for her outside, where it would be cooler. A cage or circle of fencing, with food and water inside it. Moving her out of the coop might help her get over her broodiness.
