The problem with a declaration of war is that it provides forewarning. I believe that the president should continue on his current course, asking for increased funding authority, and take action as CinC under the War Powers Act. If and when further authority is required or desired in order to achieve maximum effect we should then and only then declare war against appropriate named soveriegn countries.
That means that if Afghanistan, the Sudan, the UAE, Algeria, Libya etc. attempt to prevent or impede unilateral actions against known terrorists and conspirators that they will then fall under the harboring provision of his statements. A Declaration of War based on the grounds of an alliance with known enemies of the United States would then be appropriate. The President does not need a DoW to act, he only needs it to sustain action or if a head of state (as recognized by the US DoS is a potential/likely casualty.