As far as I can see there are only two options: Either really use JavaScript and replace the part of the DOM that contains the stats, or use an <iframe> with an automatically refreshing page inside. I don't think it is possible to refresh the whole page and at the same time keep the plug-in running.
The <iframe> should be very straight forward, but might show some flickering during the refresh. The JavaScript way is a bit more involved, but it could do seemless updates of the page and also real-time updates become possible using a WebSocket connection.