girlies have stopped laying

Hi everyone,
Hope you can help my three ex bats stopped laying in October, we thought it was probably due to the short days, but they have not resumed laying yet and I was just wondering whether they had stopped completely?
We got them last Easter and they laid reguarly everyday until about september when they gradually stopped laying until we only had the occational egg.
I'm not sure how old ex bats are when they are rescued, but i thought they'd lay a bit longer than this! Is there any other reasons they would have stopped laying and is there any way of getting them started again or have they retired gracefully?
Thanks
Angelina