Have you considered remarketing yet?
Search Engine Journal has a great article on the power of remarketing. Below are some selections from it, and the link to the full article.
“Conversion rates actually increase the more users see an ad within remarketing campaigns. It’s true that click-through rates decline over time, but those people who do click on your ad, after having seen it a few times already, become twice as likely to convert!… Remarketing gives people a gentle reminder to finish what they started on your site, while reinforcing your branding and messaging to that user every time they see you.”
“People stay interested in (remarketing ads) for twice as long as regular display ads, and convert at higher and higher rates with each incremental ad view.”
“Just 18 months out, remarketing allowed us to increase our repeat visitors by 50%, boost conversion by 51%, and increase time on site by an insane 300%! Remarketing helped make our SEO 7x more awesome by keeping us in front of interested consumers and compelling them to take action.”