you have to do the seo for your site...Build more traffic on your site to increase revenue from adsense.
The thing with Adsense is the traffic, the more traffic you get the more chances someone will click your ad, it's a no brainer that the high traffic sites get the most Adsense revenue, so if you can get that traffic following simple SEO, then your Adsense earnings will increase
Good quality articles -> So many back-links from other blogs -> Higher ranking in Search Results -> More traffic -> More revenue