Aggiungi questo codice
codice:
Sub EmptyText(ByVal ctrl As Control, ByVal emptyt As Boolean)
    If emptyt Then ctrl.Text=""
    For Each c As Control In ctrl.Controls
        ctrl.Text = ""
        If ctrl.HasChildren Then EmptyText(c, True)
    Next
End Sub
e al posto del For Each del tuo codice inserisci
codice:
EmptyText(Me, False)
.