When expanding the functionality of a workflow to compute the sum of three numbers instead of two, and having to update the test data in an Excel file accordingly, you would generally need to:

Open the Excel file that contains the test data.

Add a new column for the third number (e.g., Number3).

Fill in the data for the new column with the appropriate values for the test cases.

Save the Excel file with the updated data.

Refresh or update the data source in the test case to reflect these changes.

This is because "Refresh Test Data" suggests that the test case will re-import or re-read the test data from its source, which in this case is the updated Excel file with the additional Number3 column. "Update Test Data" might also seem appropriate, but it typically refers to a scenario where you need to update the test case's reference to the data, not the structure of the data itself. "Add Test Data" and "Remove Test Data" are not appropriate as they imply adding a new data set or removing an existing one, rather than refreshing or updating the existing data set with the new column.