www.getmonetizer.com
www.ytz.com
Run pops to both.
If you want them to come back, cookie them and follow them on facebook with ads showing more (similar) content.
Check out earnify.com for good cpm on your native ads blocks.
And as jennatalia said, pixel the s*it out of them to hit them later on with similar content.
Mehdi
Hit them with a newsletter, make them like your page, stuff like that