Cost per click is going downthehill for many adsense publishers. It could be a sign of low inventory for Google Adsense but most probably it might be the niche you are in and the kind of traffic you are getting. You can also try using the page ad specifically meant for mobile users to improve your income.
Brother first of all you need to do seo of your website and also share your quality post in social media , then you wanna increase your cpc , so you do some works like first of all use high bid keyword for your content , second thing you need to block low paying ads on your adsense
Everything, my friend, depends on the way you think about making money online. There are few ways to use in order to improve the amount of money you make. 1) Choose the better niche. 2) Improve the amount of valuable information you deliver. 3) Play with ads (it's impossible to provide you with advice without url). and so on... But I assue, your niche is not finance, real estate, or stock market. And this is the main reason!