Do I need to re-pitch yeast?

So I was cooling down a pumpkin milk stout about midnight last night and apparently my thermometer is now a little off. I ended up pitching yeast at 83 degrees, it was a dry packet of Safale US-05 which says the highest temp should be 77. My wort is now at 76 degrees and the little plastic cup (not sure if there's a name) has moved up to the top of the airlock, so it looks like there is some fermentation starting. Should I worry that it won't be as vigorous as it should be and re-pitch another yeast?

You should worry that it will be MORE vigorous than it should be. 83 degrees will not kill yeast.... it will make them ferment too vigorously, driving fermentation temperatures up and creating off flavors and "hot" alcohol flavors in your beer. Get that baby cooled down....down into the mid 60's if possible. The vast majority of all ale fermentations should be held in the mid 60's, give or take a little, for optimal results.

The yeast didn't die, the max temp is for decent fermentation. Yeast can live well into the 100+ range.

wow, thanks brothers, good to know!

My general fermentation on most ales is to chill them to 58-62 degrees. My basement sits at about 62 degrees. Pitch yeast. Temp will rise to 62 over a couple days and then as the yeast is fermenting it will generate its own heat and gradually the temp. will freerise to 66-68 at peak of fermentation..... when I see it seems to be holding and starting to fall back toward 67-66-65 (day 5-7 usually) I will bring it upstairs where it is 68-70 and let it finish out at that temperature until day 10-12 or so. Then I take it back to my brewroom in the basement, put it up on the counter in preparation for transferring to keg in 2-4 days. This allows the beer to settle, dry hops to settle, etc..... then on kegging day, I don't have to move my fermenter and it has had a chance to remain still and clear up before transfer.