An empire that had already swallowed the poisoned pill that was the Concordat was not about to "pounce" on a limping gerbil. It was psychologically whipped. As it still is a generation later, but presumably even more so when the scars were still bleeding.
Apart from anything else, it had not had the opportunity to rebuild any kind of intelligence operation. So it would have been in no position to even know what, if any, forces the Dominion still had in reserve.