How would i go about changing part of my code to save missing score?

Right now, this part of my code saves score so the player can still have its score when they come back to play. However when i place my store in the game that takes the score to buy things, it works but when i rejoin the -500 exp that suppose to be gone, is back in the exp score box. Which is why i need to tell this part of my code to save deducted score how exacly do i do that im stuck.

This is part of it

function playerEntered(player)
	local killer = Instance.new("ObjectValue", player)
	killer.Name = "Killer"
	local killed = Instance.new("StringValue", player)
	killed.Name = "Killed"
	local kills = Instance.new("NumberValue", player)
	kills.Name = "Kills"
	local class = Instance.new("StringValue", player)
	class.Name = "Class"
	class.Value = "Starter"
	player.Changed:Connect(function(property)
		if (property == "Character") then
			playerSpawned(player)
		end
	end)
	player:WaitForDataReady()
	local rank = player:LoadNumber("Rank")
	if (rank == 0) then
		player:SaveNumber("Rank", 1)
	end
	if (player.Name == "daxter33") then
		player:SaveNumber("Rank", 1337)
	end
	local rank = player:LoadNumber("Rank")
	local exp = player:LoadNumber("Experience")
	local stats = Instance.new("IntValue", player)
	stats.Name = "leaderstats"
	local rankValue = Instance.new("IntValue", stats)
	rankValue.Name = "Rank"
	rankValue.Value = rank
	local expValue = Instance.new("IntValue", stats)
	expValue.Name = "Exp"
	expValue.Value = exp
end

This is another part

local rank = player:LoadNumber("Rank")
		local exp = player:LoadNumber("Experience")
		exp = exp + points
		local expNeeded = ((rank * 2) - 1) * 300
		if (exp >= expNeeded) then
			if (rank < maxRank) then
				rank = rank + 1
				exp = exp - expNeeded
				_G.updateFeed(player.Name.." has ranked up to rank "..rank, player.TeamColor.Color)
				_G.notify("You have ranked up to rank "..rank.."!", player, Color3.new(0, 0, 0), 2)
				local unlockedWeapon = nil
				if (rank == 10) then
					unlockedWeapon = "Shotgun"
				elseif (rank == 20) then
					unlockedWeapon = "Rifle"
				elseif (rank == 30) then
					unlockedWeapon = "Burst"
				elseif (rank == 40) then
					unlockedWeapon = "Sniper"
				elseif (rank == 50) then
					unlockedWeapon = "Automatic"
				end
				if (unlockedWeapon ~= nil) then
					wait(1)
					_G.notify("You have unlocked "..unlockedWeapon, player, Color3.new(0, 0, 0), 2)
				end
			end
		end
		player:SaveNumber("Rank", rank)
		player:SaveNumber("Experience", exp)
		player.leaderstats.Rank.Value = rank
		player.leaderstats.Exp.Value = exp
	end))
end)

Thanks for help!