Replaying the miracle extension will not allow you to send another Tornadus to your game. Each game save of the Dream Radar allows one transfer of each legendary to only one game. So, you wouldn't be able to catch Tornadus and send it to both a Black 2 and White 2 game, for example.
You can delete your DR save and redownload the game to start a new file, but you will not be able to send another copy of Tornadus to your game, as that is another one time only thing.
So, your options at this point are to trade for one, or find another copy of BW2 you can use that hasn't received Tornadus yet, then transfer over another one.
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Question... If I started a game on a White 2 version and got all the three therians plus Ho-Oh and Lugia transfered to that White 2 game and decided I wanted to transfer those legendaries to my Black 2 then start a new game on White 2 and a new file on Dream Radar, would I be able to capture those legendaries and transfer them to the new save file on White 2? Sorry if it's confusing. But basically, imagine I caught all legendaries and sent them to a game, then made a new game and a new save file on Dream Radar. Would the new save file on the BW2 game be able to receive the legendaries?