First of all, I personally think Kenny is dead. As much as I loved his character (even if I didn't always agree with him), I personally think he's gone. If he is dead, telltale will most likely have a walker Kenny somewhere in season two, maybe as part of a herd that left Savannah.
But what if, by some chance, he lived? How do you think telltale would bring him back?
Here is one possibility I thought off. I'm guessing a lot of the game will be determining who you trust. Imagine having a character in your group that has helped you out and seems trustworthy. That character gets attacked by a walker and you pull out a gun, ready to shoot it. Then, Kenny appears from behind a building, and gets tackled by a walker. Then you have to choose between someone you had a connection to in season 1, who we know wouldn't hurt Clementine (unless he's gone completely insane), or a character that has helped us out recently.
I doubt telltale would do that, but it would be interesting to see who players would choose.