I would not recommend shimming a take down bow limb at all.....
The only way you can increase the draw weight on the existing limbs is cut the limbs down an inch on each end and put new tip overlays on..... This isn't a procedure i would recommend unless you have experence with bow building. you can get as much as 4-5 pounds...... BUT....
The problem with doing this is that it changes the whole geometry of the limb design in a recurve, and may shorten the stacking point.....
last option is find a bowyer who will build new limbs for it...