Usually, orders deliver immediately. But sometimes, it may have some delays. If it happens, it means that your purchase is being processing. No need to try and buy them again.
Sometimes, all you need to do is a fresh connection with the server. Try to restart the game, this may speed the process along.
If you still have not received your purchased item for more 24 hours, please contact iTunes support, as Apple process all payments of the game. You can contact them to get things done.