It's natural .... the original advertisers have moved on possibly to a new niche, new campaign, new key words, not a lot you can do .... maybe try a new post and update the page ....
i suddenly saw some very steep decrease in wide vertical banner ad ... so as suggested my one of the members here i switched to adlink unit ... thanks !!! i am again getting $0.50+ !!!
I imagine a key point might be where the traffic and clicks are coming from ... like someone else said "I got banned from AdSense" thread coming soon.
Traffic was a major problem for me too. But a guy on DP was selling the ad space in his website for $1 a day. I get traffic from there ... Now i get some 20 clicks average a day on adsense
Congratulations to you, but so many report success with little content, I don't understand how they do it...?