There are just so many different ways you can do this. Some of that depends on how you manage them, do yours forage for a lot of their food or do you buy practically everything they eat for example. That can affect the economics.
Since you are using the hen's for stew/soup I'd suggest you feed them as you would laying chickens only. Let your meat birds take care of your meat needs. I'm canning chicken broth today, just taking a short break after lunch. I'm using dual purpose chickens raised for eggs, nothing special for meat. The broth flavor is tremendous. And I'm picking meat off the bones from the carcasses, that usually goes to sandwiches for my lunch but works for tacos, casseroles, or soups.
My main laying/breeding flock is one rooster and about 8 hens. I hatch a bunch for meat each year and select four replacement pullets each year. Pullets often skip the molt their first fall/winter and continue laying throughout the winter. I'll keep these the following laying season, feed then through their first adult molt, and keep them the next laying season. Then they go to the freezer when they start to molt. So I take four adults hens and four pullets through each winter and I pretty much always have eggs.
Some people do it exactly like you are thinking, replace the entire laying flock every two years. Just try it and see how you like it. If it works for you, great. If not, be flexible and try something else.
Good luck!