1. If I could do my life (all) over (again), I would have made better use of time.2. If I could live my life over, I would have married you.
要是我能夠再活一次 = If I could do my life (all) over (again) 或 If I could live my life over
When a man and a woman start dating, they need to go through an adjstment period before they decide to marry each other.