Getting Custom Inventory to Update?

basically simpler checking the players level and determining on what to set the clay... (i know there are simplier ways but i find it easier to use this). I was wondering on how to constantly update this inventory so if they rankup the red clay will turn into green?

Code:

   if(cfg.getInt(player.getUniqueId()+"."+"rank")>=4){

        ItemStack sonic = new ItemStack(Material.STAINED_CLAY, 1, (byte) 5);

            ItemMeta sonicmeta = sonic.getItemMeta();

            sonicmeta.setDisplayName(ChatColor.translateAlternateColorCodes('&',"&a&lSonic"));

            sonicmeta.setLore(Arrays.asList(ChatColor.AQUA+"Recieve Speed 5 after a kill",ChatColor.RED+"REQUIRES LVL: 4"));

            sonic.setItemMeta(sonicmeta);

    inv.setItem(7,newItemStack(sonic));

    }else{

        ItemStack sonic = new ItemStack(Material.STAINED_CLAY, 1, (byte) 14);

            ItemMeta sonicmeta = sonic.getItemMeta();

            sonicmeta.setDisplayName(ChatColor.translateAlternateColorCodes('&',"&4&lSonic"));

            sonicmeta.setLore(Arrays.asList(ChatColor.AQUA+"Recieve Speed 5 after a kill",ChatColor.RED+"REQUIRES LVL: 4",ChatColor.GRAY+"LOCKED"));

            sonic.setItemMeta(sonicmeta);

        inv.setItem(7, new ItemStack(sonic));

    }

 

The problem i had was trying to get a method that updates inv (Inventory inv = Bukkit.createInventory(...)

 

Thanks! worked like a charm!