NPC sheets don't auto-calculate from stats. That is (other than a condensed view) the point of the npc sheets, because it cuts down on the javascript sheetworkers needing to run. If anyone else is using the summons that doesn't have the feat, then it might be best to put in notes in the various roles to remind you that something needs added (attack/damage and fort saves) and just remember to bump the hp by 2 per HD. If you are the only one that is summoning these things, I would suggest that the GM of your game create a folder for summons, and create a sheet for the ones you most commonly use. Change the name of them to add summon at the end, which will allow regular versions to be dragged out from the compendium (the compendium won't overwrite and existing journal entry with the exact name of what you are dragging out). That way, you could conjure a "Wolf Summon" from your journal folder, but the GM would still be able to generate a "Wolf" from the compendium. Then you edit the "Summon" creatures with the values they should have by directly editing the attack/damage rolls, fort saves, and any skills affected by strength. The GM would also need to alter the default hp on the token and resave that as the default token on the sheet.