After you create a new report or open an existing report, you are then able to refresh the data in that report.

To refresh the data in the report click on the 'Refresh Data Icon in the outlook bar or toolbar.

Alternatively...

Click on 'Data' and then 'Refresh Data' in the menu.

This will start the Run Query Wizard to refresh the report data.

Once the query has been run, the data in your report will be updated.