You can create a recordset that will return all of the pages and use that to have the menu update automatically. The recordset query would look something like:
SELECT C2.ContentGroup, C2.ContentPageSetOrder FROM pcms2_contents AS C1 LEFT OUTER JOIN pcms2_contents AS C2 ON C2.ContentPagesetParentID = C1.ContentID WHERE C1.ContentGroup = '[YourTemplateGroup]' AND C2.ContentPageSetOrder IS NOT NULL GROUP BY C2.ContentPageSetOrder ORDER BY C2.ContentPageSetOrder DESC