By default, the real-time data mode displays the graphs with data for the last 7 days.
You can add filters, or refresh the data after a specific time duration. You can view data from the time Analytics Server is configured till the present time, but the data that is older than 7 days will not be displayed.
For more information about applying time-filters, see Section 19.9.5, Adding/ Modifying Refresh Time for Real-time Dashboard.
For information about the actions that you can perform on a dashboard, see Section 19.9, Managing Analytics Dashboard