Even though there are lots of things I'd rather not have done in the way I did,
I probably wouldn't change much because I might lose things that are important to me if I do (keeping the Chaos Theory in mind).
The ability to alter time (to let it run faster or slower, also goes for different things running in different time dimensions)
rather than turning it back is not only more realistic, but also more interesting for myself.
You could, in a way, stop aging or gain superhuman abilities (not only reflexes, just think about acceleration, force x speed, etc) doing so.
At that point, I really don't know yet what I'd do exactly, but I'd want to find out to what extent I can manipulate time for sure :P
It wouldn't really be a problem to gain large amounts of money with those abilities, although,
if I had them, money would lose almost all value for me anyways.