If I understand the question correctly you should be able to subscribe to the podcasts from iTunes and it d/l's all the new podcasts once they are available. You can go to preferences and set the frequency that iTunes checks for new podcasts. I usually have it check once a day. I have several that I have not listened to yet but it still d/l's the new ones.
It just stops updating them and puts an exclamation point next to them. It does allow you to resume updating them without subscribing again if you right click on the podcast heading and hit "Update Podcast". Any episodes that are no longer available will be missed.Oh. I didn't know that. I guess I listen to them often enough to keep them downloading. Does it erase it entirely from the podcasts? Or would be be able to hit unsubscribe and then subscribe again to start the process over?