I would suggest posting people, maybe once a month interesting articles.
Other sites do this, and it shows me that the content is active, interesting and relevant to why I subscribed to a website in the first place. You could include an opt-out for those who do not like this.
Even if you posted a summary of the best topics in a month, maybe with summary, this would maybe get me visiting more. Show me where it is interesting, I would be willing to highlight my interest areas!
I am not a regular visitor because I had forgotten you exist!