How would i make improve this script so that it will run when a model is added to workspace?

as well as keep the if distance > 75 then thing running so as soon as the distance is greater than 75 it will delete them?

local player = script.Parent.Parent.Parent
table.foreach(workspace:GetChildren(),
	function(i,v)
		if v.ClassName == 'Model' and v ~= player and v.Torso ~= nil then
			local distance = (player.Character.Torso.Position-v.Torso.Position).magnitude
			if distance <= 75 then
				local billgui = Instance.new('BillboardGui',script.Parent)
				local infogui = Instance.new('TextLabel',billgui)
				billgui.Active, AlwaysOnTop, Enabled = true, true, true
				infogui.Active = true
				billgui.Size = UDim2.new(0,100,0,100)
				infogui.BackgroundTransparency, BorderSizePixel = 1, 1
				infogui.Position = UDim2.new(0,-50,0,0)
				infogui.Size = UDim2.new(0,200,0,50)
				infogui.FontSize = 'Size24'
				infogui.Text = (v.Name)..' Lvl: '..(v.Level.Value)
				billgui.Adornee = v.Head
				if distance > 75 then
					billgui:remove()
					infogui:remove()
				end
			end
		end
end)

Try using the ChildAdded method. It fires when a child is added to a specific place. Try this code below (It is untested):

local player = script.Parent.Parent.Parent
game.Workspace.ChildAdded:connect(function (child)
	-- Add your code here that you need, child is the object added to the workspace.
end)

This code can be modified, but should work fine for your purposes! I hope this helps, unless I read the entire question wrong.