I actually don't think I'd re-do any one year of my life because where would I be if I didn't make those mistakes? Even if I didn't make one of those minor mistakes, my entire life could be different so why mess with it?
Probably the last year of my life. I'd have gone home to visit my granny before she died unexpectedly. I'd have thought a little more about my after university life. And I'd have appreciated the joys of university a little more