You may discover that you need to add more fields from the data source after the report was created. You can add fields to an existing report without creating an entirely new report. To add fields to an already created report, select the main node of the report from the outline view (in this example is named "coffee"). From the properties tab press the button Edit query, filter and sort option, as shown in the following figure

In the dialog that appears, you can specify a new query and by clicking the button Read Fields and then "OK". All the fields discovered are added as new fields in the report. Note that if the new query discovers fewer fields than the ones used in the existing report, the fields that are not included the new query will be removed from the report. An example can be seen in the following figure:

As you can see, we selected only the fields ORDERID and CUSTOMERID, so any field previously added to the report that is not included in these two will be removed. This dialog is very powerful - from here, you can change the data source, add, remove and reorder the fields discovered by the new query.