Rebuild thumbnails after database table corruption

Somehow, my WP “postmeta” table in MySQL was corrupted this week. I restored a backup I had from four months ago, but all the newer entries have missing thumbnails for the photos. Is there a way to have WP rebuild the thumbnails for me? If not, do I have to delete and re-upload each one? At least I had a backup of the previous three year’s worth of posts!