The quick and dirty way would be to use error handling. Here is another way:
Code:
Private Sub Document_ContentControlBeforeDelete(ByVal OldContentControl As ContentControl, ByVal InUndoRedo As Boolean)
Dim lngIndex As Long
Dim oCC As ContentControl
Dim ContentCtrl As ContentControl
Dim Counter As Long
Counter = 1
For lngIndex = ActiveDocument.ContentControls.Count To 1 Step -1
Set oCC = ActiveDocument.ContentControls(lngIndex)
If Not oCC.ID = OldContentControl.ID Then
With oCC
.LockContents = False
.Range.Text = Counter
.LockContents = True
Counter = Counter + 1
End With
End If
Next lngIndex
lbl_Exit:
Exit Sub
End Sub