What if you cut off, or picked, only the leaves so the roots could grow into a plant again in the same soil? I bet you have a long enough growing season this would be possible.
We did this last year with the cabbage and got some usable leaves that came back up but not whole plants...usable for salad anyway and it taught us something.
that's what I do. the romaine lettuce is best for that. I started out with a head of lettuce and it worked well.
so I vote FACT
but I wouldn't use store bought