If your podcast feed has been submitted and accepted by iTunes, it will get updated automatically by iTunes. If you haven't done so yet, you can submit your feed to iTunes.
1. First, please make sure the episode file format is supported by iTunes. Please see our FAQ about iTunes supported formats here.
2. Second, just be patient and wait. Based on our observations, it looks like it is taking longer and longer to get podcasts updated in iTunes.
3. Third, if you really don't want to wait, you might ping iTunes. However, too frequently pinging iTunes might have negative effects as iTunes might think it is a SPAM.