Is there a way to do a check for something every 30 seconds?

I've got a script that will change your tool when you press a button, and it then goes up and down in order of your tools. However, I ran into the problem that if you pick up a new tool, then the new tool will not be included in the list that has the children of the users backpack. Here's the script:

local lpress = 0
local rpress = 0

userInputService.InputBegan:connect(function(input, processed)
    if input.UserInputType == Enum.UserInputType.Gamepad1 then
        if input.KeyCode == Enum.KeyCode.DPadUp then
            game.Players.LocalPlayer.Character.Humanoid:UnequipTools()
            lpress = 0
            rpress = 0
        end
    end
end)

local tools = game.Players.LocalPlayer.Backpack:GetChildren()
local items = {tools[1], tools[2], tools[3], tools[4]}
userInputService.InputBegan:connect(function(input, processed)
    if input.UserInputType == Enum.UserInputType.Gamepad1 then
        if input.KeyCode == Enum.KeyCode.DPadLeft then
            if lpress == 0 then
                game.Players.LocalPlayer.Character.Humanoid:EquipTool(items[10])
                lpress = lpress + 1
                rpress = 10
            elseif lpress == 1 then
                game.Players.LocalPlayer.Character.Humanoid:EquipTool(items[9])
                lpress = lpress + 1
                rpress = 9
            elseif lpress == 2 then
                game.Players.LocalPlayer.Character.Humanoid:EquipTool(items[8])
                lpress = lpress + 1
                rpress = 8
            elseif lpress == 3 then
                game.Players.LocalPlayer.Character.Humanoid:EquipTool(items[7])
                lpress = lpress + 1
                rpress = 7
            elseif lpress == 4 then
                game.Players.LocalPlayer.Character.Humanoid:EquipTool(items[6])
                lpress = lpress + 1
                rpress = 6
            elseif lpress == 5 then
                game.Players.LocalPlayer.Character.Humanoid:EquipTool(items[5])
                lpress = lpress + 1
                rpress = 5
            elseif lpress == 6 then
                game.Players.LocalPlayer.Character.Humanoid:EquipTool(items[4])
                lpress = lpress + 1
                rpress = 4
            elseif lpress == 7 then
                game.Players.LocalPlayer.Character.Humanoid:EquipTool(items[3])
                lpress = lpress + 1
                rpress = 3
            elseif lpress == 8 then
                game.Players.LocalPlayer.Character.Humanoid:EquipTool(items[2])
                lpress = lpress + 1
                rpress = 2
            elseif lpress == 9 then
                game.Players.LocalPlayer.Character.Humanoid:EquipTool(items[1])
                lpress = lpress + 1
                rpress = 1
            elseif lpress == 10 then
                game.Players.LocalPlayer.Character.Humanoid:UnequipTools()
                lpress = 0
                rpress = 0
            end
        end         
    end
end)

userInputService.InputBegan:connect(function(input, processed)
    if input.UserInputType == Enum.UserInputType.Gamepad1 then
        if input.KeyCode == Enum.KeyCode.DPadRight then
            if rpress == 0 then
                game.Players.LocalPlayer.Character.Humanoid:EquipTool(items[1])
                rpress = rpress + 1
                lpress = 10
            elseif rpress == 1 then
                game.Players.LocalPlayer.Character.Humanoid:EquipTool(items[2])
                rpress = rpress + 1
                lpress = 9
            elseif rpress == 2 then
                game.Players.LocalPlayer.Character.Humanoid:EquipTool(items[3])
                rpress = rpress + 1
                lpress = 8
            elseif rpress == 3 then
                game.Players.LocalPlayer.Character.Humanoid:EquipTool(items[4])
                rpress = rpress + 1
                lpress = 7
            elseif rpress == 4 then
                game.Players.LocalPlayer.Character.Humanoid:EquipTool(items[5])
                rpress = rpress + 1
                lpress = 6
            elseif rpress == 5 then
                game.Players.LocalPlayer.Character.Humanoid:EquipTool(items[6])
                rpress = rpress + 1
                lpress = 5
            elseif rpress == 6 then
                game.Players.LocalPlayer.Character.Humanoid:EquipTool(items[7])
                rpress = rpress + 1
                lpress = 4
            elseif rpress == 7 then
                game.Players.LocalPlayer.Character.Humanoid:EquipTool(items[8])
                rpress = rpress + 1
                lpress = 3
            elseif rpress == 8 then
                game.Players.LocalPlayer.Character.Humanoid:EquipTool(items[9])
                rpress = rpress + 1
                lpress = 2
            elseif rpress == 9 then
                game.Players.LocalPlayer.Character.Humanoid:EquipTool(items[10])
                rpress = rpress + 1
                lpress = 1
            elseif rpress == 10 then
                game.Players.LocalPlayer.Character.Humanoid:UnequipTools()
                rpress = 0
                lpress = 0
            end
        end
    end
end)