saam4 Just taking a look, your revenue hasn't really dropped off, it has been fairly consistent since January this year, albeit a little lower right now. However, as the growth data in the dashboard suggests, traffic is also slightly down so that would help explain the revenue drop.
Your ad setup looks pretty good too, you don't have any ad restrictions set up and there is a decent number of ad types and ad positions enabled.
One thing to consider is that you also haven't been producing new content (see screenshot). You want to make sure you're constantly adding new content and updating old content to assure your ranking doesn't take a hit in search results.