Yes, if she's a stubborn broody it will kill her to go another round.
its bedt to break 'pointless brooding ' by using a dog cage with no bedding but a roost so she has nowhere to nest.
One of my hens has been going for a few weeks now without sitting on anything at all. She’s so stubborn and almost impossible to break. However I am now trying my hardest to break because as mentioned if they go any longer it can be really dangerous.
If you still wanted chicks though you could find some day-olds locally and try put them under her? Then she won’t have to go through the 21 day cycle again or sitting on the eggs. If all goes well she will just raise them, and she will think the non-fertile eggs she has been sitting on have hatched.
Have a backup brooder just incase she rejects them though.