So how do I make this script repeat after a Player has died?

game.Players.PlayerAdded:Connect(function(player)
	player.CharacterAppearanceLoaded:Wait()
	player.Character.Humanoid:RemoveAccessories()
end)

You could attach a CharacterAdded event inside your PlayerAdded event to so that it fires every time a new character is created which happens every time a player dies,

game.Players.PlayerAdded:Connect(function(player)
	player.CharacterAdded:Connect(function(character)
		local humanoid = character:WaitForChild("Humanoid")
		humanoid:RemoveAccessories()
	end)
end)