Browser Data Posting

I display data in several widgets that are supposed to present the last 2 hours of data. Following refresh of the browser, two hours are correctly displayed. However, following the refresh as new data is acquired and displayed, the far left X value (two hours before the refresh) does not change. Data will continue to accumulate until the browser is again refreshed. i.e. 2 hours after the refresh, 4 hours of data will be displayed.