You can always increase income by having more unique content, and getting more and more backlinks, the thing with Adsense is it takes time
Target good keywords for SERPs and optimize you website's in term of On page SEO and do quality off page work, with this you can get more potential visitors to your website and CPC depends upon quality of your visitors. This is the only way to increase income from adsense (potential and relevant traffic ).
If you want to explore alternatives then this will be helpful The Top 10 Alternatives to Google Adsense onecoolsite.wordpress.com/2009/01/22/twenty-income-streams-for-bloggers/
It is best explained theoretically many times everywhere on the net but very few achieve it practically. Try your luck at these tips and let us know.