How to get them laying again?

With the weather change, my egg production has gone from over 30 daily to around 5 per day.   First, the ameraucanas quit...no green eggs for well over a month.  Next the brown leghorns gave out--haven't seen a white egg in 2 weeks and they used to lay every single day.  Even my brown egg layers have slowed, but at least I get 5/day.

How can I get them to start laying again?  Three flood lights are on a timer in the coop to add around 3 hours of light in the morning and evening.  Is there anything else I can try or do I have to wait until spring?  It is getting rediculously expensive to feed these non-producers.

PC

They are eating tons of commercial layer crumbles and have plenty of fresh water on a heated base so that it doesn't freeze.  They eat minimal amounts of oyster shell.

The coop has some windows and a corrugated fiberglass roof that allows in some daylight, but I'll admit that it is maybe a little dim on these gray wintry days.   This morning, I adjusted my timer so that the lights will turn on three hours before sunrise and stay on throughout the day until 3 hours after dusk.   They have been turning off at sunrise and remaining off during the day, so I'm experimenting to see if more light during the day will help.

They have access to an enclosed run, but the ground is bare dirt at this point.  I toss table scraps in there but there are no bugs/grass to be found anymore.

Maybe 2 out of 45 are losing feathers and looking kinda ugly, so molting could be a factor, but my ameraucanas and leghorns look great and are not laying at all.

How long should I expect them to be freeloaders?  (eating but not laying)
PC

Lets see, I got my first eggs August 7th from my 21 weekers, so that makes my oldest around 38 weeks.  Some are 34 weeks.  Others, including the ameraucanas are around 28-30 weeks.  I also have some younger gals that aren't laying age yet.
PC