Reset all votes on a content type every week
There's many ways to accomplish this. The voting data for the Voting API module is stored in the votingapi_vote &amp; votingapi_cache tables. Essentially, you need a way to target the vote data you wish to eliminate in these tables (e.g. via a DB query) and then build some process on which to regularly execute it (e.g. a cron run). 

A crude example would be a custom module that evokes hook_cron() to check the last query execution and fire it if it hits its time threshold:

/**
 * Implements hook_cron().
 */
function MYMODULE_cron() {

  // Clear the vote every week.
  $vote_clear_timestamp = variable_get('MYMODULE_vote_clear_timestamp', 0);
  if ($vote_clear_timestamp &lt;= strtotime('-1 week')) {

    // A more targeted process would use db_delete() to target criteria
    db_query("TRUNCATE {votingapi_vote}");
    db_query("TRUNCATE {votingapi_cache}");
    variable_set('MYMODULE_vote_clear_timestamp', time());
  }
}