On mission one, just before you rescue the first captive, save the game. Now, as soon as you have rescued him and moved on to mission 2, reload the game and rescue him again. Now, when you finish the level you’ll be on level three. Redo this until you are on the level you desire.
If you hang on to the data crystal after the first mission, you can use it to find other captives on the other missions without hunting for clues.