Sub wlepa()
Dim co As Variant, wiersz As Long, kolumna As Integer, ostatnia As Long

'ustalamy ile wierszy posiadają nasze dane
ostatnia = Columns("A:C").Find(What:="*", After:=Cells(1, 1), _
    SearchOrder:=xlByRows, SearchDirection:=xlPrevious).Row
For kolumna = 1 To 3
    For wiersz = 1 To ostatnia
        If Cells(wiersz, kolumna) <> "" Then
            co = Cells(wiersz, kolumna)
                Else
                    Cells(wiersz, kolumna) = co
                        End If
    Next wiersz
co = ""
Next kolumna

End Sub