Inserting a row in a pdf table?

We are completing a long grant application in pdf. The document has many tables where our text is entered or the original text is to be edited by us. Often there is textnote in the last row to "(insert additional rows as needed)". I've searched and tried all of the tools I can find but no luck adding another 4 cell row onto the table. We're running Acrobat Professional v8. Please help.

Mark