a 1 1/2 in draw length change is a awful lot if the bow is not draw length adj.you may have to change cams.buy shortening it that much your brace height and a/a will be well off and will effect the effiencey of the bow itself.if its draw length adj just make sure the string and cable are the correct length and reinstall.that should get your cams back pretty close to time i would imagine.if its not close take it to the shop and see if they can help you out.