Hen Sleeps in the Nesting Box

My 3 year old EE has always had issues. She was the first of my flock to lay, but then her eggs would be soft shelled, or no shell for a long time. I don't think she lays at all anymore. She eats and drinks fine, but she is mostly just standing around. She doesn't have much get up and go anymore. Lately I've noticed she's been sleeping in the nesting box. I've been pulling her out of there every night for the past week and sticking her up on the roost. I'm not sure, but I'm suspecting that for some reason she can't get up on the roost. Maybe she isn't strong enough, or maybe her eyesight is weak. I really don't know, but it's kind of a pain in the rear having to do this every evening. Does anyone have any experience with this? Thanks!