Place maximum ads are display ads, otherwise you can use text ads, but you have to change color for more attractive. And ofcourse you need much more quality traffic from search engines that will assist you to make more money using google adsense.
If you are already making money with Adsense then it will be not more difficult to make you more just make your content more engaging, increase the visitors of your site by doing marketing of your website online and offline. As the visitors on you site increase the income will increase.
You can apply these ways to increase traffic and also revenue from Adsense for your site.
Placed ads on proper side.
Need more traffic for your site, using SEO and IM techniques.
Good and unique content on site
Make your site unique with other sites.
Improve On-page SEO for your site.
Promote on social media such as Facebook, twitter, Google+, Linkedin...etc.