NPC follow script breaks when the NPC dies?

Last time I had trouble with the NPC follow script not working when the player dies, but now it's when the NPC dies the follow script stops working. I've tried cloning the script in many ways when he dies but that doesn't seem to work. Here is the follow script:

function ready(tmp_plr)
game:GetService("RunService").Stepped:connect(function()
local yes, error = ypcall(function()
if (math.abs((tmp_plr.Character.Head.Position-script.Parent.Head.Position).magnitude)) < 90 then
script.Parent.Humanoid:MoveTo(tmp_plr.Character.Head.Position)
end
end)
end)
end
game.Players.PlayerAdded:Connect(function(p)
ready(p)
end)

Here's the script that makes him respawn:

robo = script.Parent:Clone()
while true do
wait(0.1)
if script.Parent ~= nil then
if script.Parent.Humanoid.Health < 1 then
wait(10)
script.Parent.DetectionScript:Destroy()
game.ReplicatedStorage.DetectionScript:Clone().Parent = script.Parent
robot = robo:Clone()
robot.Parent=script.Parent.Parent
robot:MakeJoints()
Instance.new("ForceField",robot)
script.Parent:Destroy()
wait(5)
robot.ForceField:Destroy()
end
end
end

"DetectionScript" is the name of the follow script, and I made a duplicate in ReplicatedStorage but that didn't seem to work well. I also tried to put that line under robot.ForceField:Destroy() but the output said "Parent is a nil value"