Keep things fresh
Consider mixing up the format of your episodes to keep your audience engaged.
Don't be afraid to change your format.
Most podcast have an established format of some sort. Having a format is a good foundation but don't feel you have to rigidly stick to that format all of the time.
Shorter episodes are very impactful.
If you normally do longer shows, consider throwing in some shorter "mini" shows. These create great engagement in accessible chunks.
Use your back catalogue.
Podcast are evergreen content so make sure to utilise them properly.
Consider creating a mini series around a key concept. If you normally release a half an hour episode on a topic, perhaps try running three shorter ten minute shows in succession to create some more bitesize content and spread out your episodes.
If your industry witnesses some important news then have the confidence to address your audience on it. For example, let's say you run a podcast interviewing film directors and a new blockbuster is announced. Why not record a quick monologue with a timely update for listeners.
When you have a fairly extensive selection of episodes already available then why not consider releasing a "best of" episode where you outline some of the highlights of the last series.
A common technique in blogs and articles which also works very well in audio form. Create a top 10 list around your podcast subject matter. For example a fitness podcast might release a "Top 10 Workout Myths" episode.
Consider alternating your interview episodes with shorter solo shows where you reflect on the points made in the interview.
In a pinch, consider re-releasing a previous episode with a fresh intro. This works particularly well if you have a long running podcast where your audience may not have heard the early episodes.
Sometimes at the end of the year, or perhaps towards the end of a series, it can be nice to do a compilation of the most downloaded episodes. For example "The top 5 downloaded episodes of 2021". You can then have a snippet from each episode and a reflection from you, the host.
Remember that podcasts are a creative medium so feel free to express yourself. Hopefully these suggestions are a good starting point, but don't feel confined by them.
Do your own thing.