Will the ingredients respawn?

I remember clearing out a loaded room at the Mages Guild in OB and nothing ever came back. It stayed empty and.... tainted. I wouldn't have done it had I known.

I take the soul gems all the time and they come back after awhile

If you have vanilla respawn time, I think they will respawn after 30(!!) in-game days WITHOUT visiting the cell.
I have a mod that changes respawn times, and it modifies the 30-day cell respawn to 7-day, so that's how I'm guessing it, because they won't respawn sooner than 7 days.