Hi Lara. Just trim it right back and save the seeds. It should have new sprouts before you know it.

I usually shake the last lot of seeds around my plants as I'm trimming it back. That tends to ensure a healthy growth of new seedlings.

To stop your next lot going to seed, trim it back regualrly, even if you don't want to use it at the time. Any extra, you can dry and save for times like you're experiencing now. Good luck.