webtop chart can present some nice high-level event summarization information in graphic form, however, it does not automatic refresh. neither chartview portlet or chart itself provides a refreshing mechanism.
I find a way of doing chart refreshing by using smart pages. following are general steps:
1. create a customized HTML, using smartpage to create a chart, then use java script to do auto refreshing.
2.copy this html file into $TIPHOME/systemApps/isclite.ear/Webtop.war/customhtml directory
3. create an iFrame and set the URL to the file, eg /ibm/console/webtop/customhtml/hello.html
To make it easy, I've attached my example html here: Chart Test Page