Earning for 15k impression per day?

I get almost 100.000 impressions per day and 50 $. I’m using ads and interstitials. Would you use ads more agressive? Right now I show an interstitials at startup and a banner in the game.

Yes, I would. As long as your active users number is growing you should monetize more - it does increase uninstall rate, but if the game is good, people won’t mind ads that much, and you can make few times more money.