I had some six year old Orpingtons still laying about three eggs a week. High producing breeds like Leghorns and sex links will "wear out" sooner than the older "dual purpose" style birds, they will lay 300+ eggs a year for a couple of years and then slow way down, while your dual purpose breeds might lay 150-200 eggs a year for a couple of years and gradually slow down.
After they molt, it can take them a while to start again, especially this time of year, because there is not enough daylight to stimulate their reproductive tract to start working again. An increase in daylight length (12-14 hours) either by waiting until the days are naturally longer, or providing artificial light, as well as a boost in protein in their diet ought to get them going again.