Hi Leila,
Whenever you have run the any employee upto specific date with live run then system update the PDC recalculation date of all that employee's in IT0003.
So in the next time if you are with forced retro efect then only i will update the DB again only maintian the date in the evaluation upto period system only start evaluating from PDC recalculation date.
Regards,
Sankarsan