There is about 2" of slack in the cables, on average. Just spend the money, and get the height you want. You can do it yourself for around $750, depending on bars you choose.
I put heritage bars on my 2013 deluxe one 1.5" risers and reused stock cables. If they were even an inch taller I would have needed a new brake line, but the others would have been good for another 2" rise at least. I did my 14" apes with new magnum cables for just under $400 all said and done.