Recurve bow draw weight?

im making my own recurve bow and i was just curious how i would add more draw weight to the bow? im looking for about a 45 to 50 lbs draw weight. Would i just add backing to it to make it thicker or do i need to make the limbs thicker when i cut it or would i curve the ends more when i do the actual recurving, or would it be a combination of the 3?