In Mass Effect 2 Lair of The Shadow Broker DLC �is it too late to change to hardcore?

Well, I wanted to delay a bit the start of this DLC, so playing on Normal i talked to Liara and she told me to meet at her apartment, and I had to take a cab. There, I went on to some other missions I had pending on Illium and the, i continued on with it. Just as I got down from the cab, the scene form Liara's apartment played, and just there I remembered to change the difficulty to hardcore. I'm alrealdy close to finish playing my 2nd playthrough... so restarting my character is not an option. Will this work? or will I have to restart from a previous saved game?