How would I make the script restart if the player died?

You should probably just make that all a function that occurs on death. Like this:

playerchosen.Character.Humanoid.Died:connect(function() --Stuff you said end)

The code cheez55 mentioned will cause the game to break if the player disconnects instead of dying. I recommend you try something like this instead:

randplayer = math.random(1,#players)
playerchosen = players[randplayer]
h.Text = "The name of the player is" ..playerchosen.Name
wait(1)
playerchosen.Character.Torso.CFrame = CFrame.new(Vector3.new(43.088, 26.76, -333.25))
-- Here's the part I added:
function RestartScript()
    script:Clone().Parent = Game.ServerScriptService -- clone the script so it restarts
    script:Destroy() -- disconnect all events in this one so it doesn't do unexpected things
end
playerchosen.Character.Humanoid.Died:connect(RestartScript) -- if the player dies
playerchosen.AncestryChanged:connect(RestartScript) -- if the player disappears from the game