Webi report headers and footers cannot be exported to Excel. SAP offers the following workarounds,

 

Workaround 1:

• Place header and footer cells inside report page.
• If you have reports with many pages, right-click each cell and select Format Cell...
• Click Layout > Vertical > Repeat on every page.

Workaround 2:

• Save the Webi document as Excel.
• Open the saved Excel file and place the table headers in the page header of Excel and it will automatically get displayed on each page.