To re-fill the new archive info structure, just go to SARI -> Status. Select the Status per Archive for the relevant archive object, and then select the archive sessions. I would do them in batches (not all of them at once). It will only process one file at a time, but, it may be a long running job which is why I would recommend to do a few archive sessions at a time.
And, yes, if you select all of the archive files, you will get back all of the entries that had been previously available plus the new field that was added.
Best Regards,
Karin Tillotson