RSL and laying issue

My RSL stopped laying in about November and has not molted and hasn't started laying again. I bought her supposedly at "point of lay" but she could have been older. I had her 4 weeks before she started laying, and laid well all of last summer. Huge eggs, with the occasionaly double yolker and occasionally also weird rubbery eggs. Her comb is red, she sits in the nest box most days, crouches when approached and seems healthy in every way. All the other girls stopped laying after she did and have started back up. I'm wondering what the signs of an internal layer might be, and what her life expectancy will be if she has become one? She's a pet, and will stay forever, but I'm wondering if there is something I can do, or is she just slow to come back to laying.

karen