The instructions on ready meals usually say once cooked, do not reheat a second time. I think in theory there's no safety reason why you can't, so long as it's fully reheated to a safe temperature. (Families in Africa and India routinely keep huge curries etc at room temperature and reheat them multiple times over several days by bringing them back to boiling point for 5 minutes).
But I'm not sure a ready meal will be all that palatable a second time round. I'd probably bin it and treat yourself to a fresh one.