If you are the ORIGINAL purchaser, and your rifle is damaged while under warranty, or due to a manufacturing defect, Colt *may* replace it for free.
If you are not the original purchaser, they won't replace it for free, and it will probably be hard to convince them to remanufacture/replace it at all, unless it is damaged to unserviceability.
Colt does not routinely replace/remanufacture pre-ban lowers, nor give any indication that they like to do so.
You're welcome to call Colt and give it a try, though - they *have* replaced/remanufactured damaged pre-ban lowers in the past, and you might be able to get them to do it again - who knows?
If you get a current production lower to replace your pre-ban, you'll still have to deal with non-milspec fire control pins - as Colt hasn't stopped that practice. New lowers also have a worse sear block than ever before (they leave a big chunk of metal unmachined in the lower between the takedown post and the selector - not just the small shoulder that SP1's and Sporter II's had).