I normally cut the used stalks off and even those that still have bloom at the very top, but for you to get alot of new bloom it might be a little too late. As you say , you can hope for new flower stalks, it can happen; they won't grow as tall tho. I was very lazy this year and didn't even pick off seed pods. That always encourages more flowers,but of course you will want some to drop and create baby plants next Spring.