The Past is But Ashes
I had a colleague that was in sales. He had a sales manager that each month would say to his team when they would hit their revenue goal, "The past is but ashes, what will you do next month?" Seems a little harsh but I guess from a sales manager's perspective you don't want your people to sit too long on their accomplishments and want to push them toward success in the next month, next quarter and next year.
Tied to this same concept is the statement, "Past performance is no guarantee of future success." In some cases, I am sure this is very true. There are some authors and musicians that are considered to be "one hit wonders." They achieve a measure of success one time and are then unable to replicate the success. Even worse, they become satisfied and lazy with their initial success and don't push themselves towards excellence a second time.
A key point in all of this is the fact that just because you were successful once doesn't mean that you are guaranteed automatic success. It will probably take just as much hard work, blood, sweat and tears as it did the first time. The nice thing about the second time is that you do have the past experience and the taste of success that drives you toward success again. Push yourself towards success again and again. Don't sit around in the ashes.