What is the ruling regarding the obligatory and supererogatory prayers performed by a person without having completed the 'Asr obligatory prayer, and what is incumbent upon him now?

You erred by exiting the 'Asr prayer until its time elapsed, but by your repentance and making up the prayer, you have fulfilled your obligation, and nothing else is required of you. Your prayers performed before making up theer are, God willing, valid.