I'd probably flipo the tips before I tried re-heat treating the whole limbs. I find that the first time heat treating you get the most out of it, and you get less and less each time after that ... assuming you did a proper job of heat treating in the first place.
As Pat said, sometimes if you add too much reflex you just get more set ... so you might add 3" of reflex, and get 2" of set ... yeah you've gained a net 1" of reflex, but if you take it too far you can end up with a bow that feels soggy and overstressed.