Expired but after exposures were done..... How to develop CN-film?

I have quite a lot of shots on CN-films 120 and 35mm which i stored in refrigerator/freezer more than 15 years ago. What is a good start to develop Colornegatives, give them a 15% push-development? maybe cut out some frames out of 120 for pushdevelopping. or risking whole film and not lose one shot.

I would give them a little extra development -- why did you not get them processed 15 years ago ?? !!

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