If it is a brood patch there isn't anything you need to do. I've actually never checked to see how long a hen has had her brood patch after being or attempting to be broody. I suppose it's there till the next moult? Maybe someone else knows.
That looks to me like a brood patch. Do they show any signs of broodiness, such as spending a lot of time in the nesting boxes, walking around puffed up, angrily squawking?