You can move an applicant out of your archived applicants' tab at any time by clicking on the select action drop-down menu and selecting Unarchive from the list.

If the applicant has a rating, the re-considered applicant will appear in both the Rated Applicants and All Applicants tabs. If the applicant is unrated, the re-considered applicant will appear in both the New Applicants and All Applicants tabs.