Everything you download from the store relating to the game (under one account) will always be available for re-download. You could do what you wanted to do (re-install) and re-install the cars you bought including the chromeline ones.
The only requirement is that you use the same account you used when you purchased/redeemed the DLC.
Edit, you could also use the "car restoration" tickets from GT Auto. They were available when you upgraded to 2.0. Those tickets will bring your car back to stock/original (some cars like chromelines aren't stock).