If you're able to give the dirt a bit of a turn, I would start with that before tossing down more bedding, I find it helps to encourage the flock into more vigorous scratching. Like
@Folly's place suggested, I put my used coop bedding into the run and have the ladies turn it into a wonderful addition to the garden come fall. They mix and turn all summer, with the occasional addition of grass clippings and yard waste, come the end of the season I fold back the top most layer, take what's underneath for the garden to break down the rest of the way with the added help of melting snow for a super rich base for spring planting.
Glad to hear your survivor is perking up for you!