God chose a new course of action in the divine councils of the Holy Trinity after the flood; He declared that He would never again destroy man in this way.  He chose mercy over wrath.  The  further expression of this resolve (regret/repentance) is that later, when He made a covenant with Abraham, it was God alone who walked the pieces, promising to take upon Himself the promise of death if the covenant would be  broken (Genesis 15:12).  So, God placed His friend Abraham in a merciful deep sleep, and He Himself walked the pieces; this is the promised self-sacrifice of the Covenant Maker.  God paid the price for that on the cross in the sacrifice of Himself, dying for a broken covenant and establishing a New Covenant.  The cross did not take Him by surprise.  It was in His heart all along!  It was the grace Noah saw, in the eyes of the Lord.  Oh my!  What love!  What mercy!  What grace! 

“When the sun had set and darkness had fallen, a smoking firepot with a blazing torch appeared and passed between the pieces.  On that day the LORD made a covenant with Abram.”  Genesis 15:17-18a (NIV)