Generally, successful monetisation stories on sites like yours that I've heard have involved creating your own product and selling it. That seems to be one of the most effective ways to move from $1.5 CPM to $15 or $150 CPM. Affiliate marketing works too, if there are useful products in the niche.

Obvious Question Is Obvious: do you have an email list? If not, I'd recommend reading around email marketing, reading Patrick's latest post on Kalzumeus, and starting one.