I noticed that my impressions began to soar early this week and my earnings plummet. When I went to some of the busiest pages on my site, I saw a whole bunch of non-relevant ads being displayed. The ads were doing really well before with serving relevant information, but it seems that they're now targeted to one incorrect keyword that was found in the page. I've since delted that keyword, but I'm still seeing ads based on it. How often is my page crawled in order to generate new keywords for ads? I have a whole new influx of people and no ads to display to them.
It should change within the day that you deleted the keyword, what you might do is write another article, or post that is enriched with your keywords to get it back on track.