If the reason that you had a planned c-section the first time was due to wrong position of the child or the placenta, there will be no reason for you why you can not deliver vaginally this time. If you had a C-section during labour the first time, take the lessons in the cahpters that you did not reach last time. so if you had a C-section during dilating, take the lessons about pushing etc, because that will be new territory for you this time around.
If you had a C-section early on in your dilating stage, then I would advise you to take the complete course. Your body will in this case respond like it is your first natural delivery.