The active player graphs don't refresh automatically. When I go to that page, it shows the last graph I saw, which may be days old. Refreshing the browser shows the new graph.
The HTTP server should be adjusted to expire those files sooner. Your server currently sets an expiration of 7 days.

Or they could just append a ? to the end of the images URL, ex http://images.vendetta-online.com/extras/daily.activity.png? which tells most sane browsers the content is dynamic and not to cache.

But yeah, I brought this up when they removed the old APL and replaced it with the graph.

Couldn't this be fixed on the server side by applying some Cache-Control: headers or something?

http://redbot.org/?uri=http%3A%2F%2Fwww.vendetta-online.com%2Fx%2Factive