The Adsense CPC (cost per click) is the amount of money you earn each time someone clicks on an ad. The cost per click is determined by the advertiser, and there is little that you can do to affect it.
As mentioned earlier, there is little you can do to affect the CPC directly. You can however make certain adjustments, if you haven't already done so, such as enabling both text, image and rich media ads on all of your ad units. Doing this should increase the number of advertisers who are competing for your ad units.
A less desirable option is to avoid using the filter list, so that you are not limiting any potential higher paying ads. Often, however, you will want to block certain ads from inappropriate websites, so this is likely the last place you would look for optimization.