If there is still availability for the exact same thing you reserved, they can cancel the original reservation and make a new one with your developer points.
If there is a waitlist, then no. The developer points that came with the most recent incentive offers can only be used at the 7 month window. If MS allowed those developer points to be "substituted" for SSR points, it wouldn't be fair to SSR owners on the waitlist.
There should not be any danger in losing the reservation if there is still availability. Reservations with developer points have to be done manually. MS will just "save" the days and the special group will take care of actually making the reservation.
Hope it works out for you.