Obligatory warning: This script has been designated as an obsoleted "Retro Script". There is no guarantee that it will function as described with modern versions of iTunes and OS X. If used in its current form it may not work at all without modification and, at worst, it may corrupt or destroy data.
iTunes will stop updating a podcast if you have not listened to at least one of its episodes in five days. This script will batch-update every podcast subscription so you don't have to manually update each one individually.
I have posted instructions on how to create a launchd agent to run this script automatically and invisibly in the background to ensure that your Podcasts are always updated.
Possible iTunes bug (July 17, 2014): Looks like the iTunes AppleScript command updatePodcast command is broken as of iTunes 11.
Perhaps of Interest...
downloaded 23s ago
Exports and then re-imports selected tracks' artwork
downloaded 26m 53s ago
Display, create text file listing info of dead tracks
downloaded 29m 37s ago
Delete characters from the beginning or ending of selected tracks' name, artist, album, comments, composer, or show tags
downloaded 30m 7s ago
Remove iTunes tracks disassociated from files
downloaded 47m 15s ago
Re-locate files of selected tracks to new folder, preserve track meta-data
downloaded 57m 1s ago
Set the Plays of selected tracks.