DO YOU WANT TO REPLACE THE EXISTING TABLE? CHOOSE
YES TO REPLACE OR NO TO APPEND THE NEW TABLE.
 
After you choose Insert Table of Contents, Word
selects the existing table and asks if you want
to replace it.
 
■ To replace the old table of contents with a
  newly compiled one, choose Yes.
■ If you want Word to add the new table of
  contents at the end of the existing table,
  choose No.
■ If you do not want Word to replace the existing
  table, choose Cancel.