Easiest way to refresh/reload a single portlet?

I need to refresh some vaadin 6.8 portlets (no push, the portlets fetch their data themselves). At first on a simple button click, later partially with a time interval.
Refreshing means, that the components are reloaded and refilled with data without reloading the whole page. I thought, that just calling the init() method would be enough, but it is not.
So, whats the most elegant way? Removing all components and adding them again?