Pages not re-indexed
 

I have a cron script that indexes a client's site:

/usr/local/bin/php -f /usr/www/users/username/search/admin/spider.php http://www.clientsite.com/ forceall

This successfully adds new pages, but modified pages don't seem to get updated. For example, there is a page that no longer contains the word "bank" but still comes up with in the search results for the word "bank". I have rebuilt the site index from scratch, which fixes the problem for now, but how can I get Phpdig to re-index existing pages?

Thanks,
Kevin