In which case, it's probably in a LINK field, for which you could use code like:
Code:
Dim Fld As Field
For Each Fld In ActiveDocument.Fields
If Fld.Type = wdFieldLink Then
Fld.LinkFormat.SourcePath = X
End If
Next
By replacing the X with the path, the path in all such fields in the body of the document will be updated.