If you aren't already doing this, it might be worth using the insights from your podcast on other outlets as well, e.g. sound bites on twitter, key insights on blog posts, and email newsletter which allows individual articles to be shared on social media easily, setting up a profile on clarity.fm for paid business consultations, carefully cultivating relationships with some journalists, bloggers who write articles related to areas of your expertise.

Also, it might be worthwhile surveying your podcast audience to find out what they like/love vs. don't like/hate (think a 2*2 matrix) about your podcast, so you can make the existing audience stickier and potentially expand the audience.