How do I re-run updates (change module schema version)?
While accessing state directly works, you can also just use the API: drupal_set_installed_schema_version(). Which actually exists unchanged at least since 4.7, as visible on the linked documentation page. Probably one of the few API functions that existed for so long ;)

To set it from drush:

drush ev "drupal_set_installed_schema_version('fillpdf', 8012)"


Note: In Drupal 7 you need to add extra include 'includes/install.inc';.