I'd say yes.
There's nothing in the feat which limits its effects to once per round, or once per power.
If the PC still has the War Wizardry feat on future rounds, the feat still works. (That is to say: if somehow the PC got this feat for only one round, then I'd think the feat would not work for rounds in which the PC didn't have it. But that can't happen under the current rules.)
Cheers, -- N