Ah tough question. Usually i would advocate you see the magnitude of the fall. if the fall is 10% or 20% its not too bad, but if you think this has reached 50%, then may be you want to put both your contribution for the year in at once.
if you do not have the money, then the decision is obvious. there is nothing much you could do.
if its a 10-20% draw down and prior to this there were some gain, your allocation should be still pretty intact. however if the draw down is 50%, your equity portion could be smaller, the rebalancing could be to sell some of your bonds and move them to equity.
Write your thoughts