Because someone who has already played the game then knows how the map is and where the other Civ's are, they generally have an advantage over the players who did not replay the game.
However, in the past, Matrix has allowed players who died relatively early in the game to replay it since they had not 'spolied' much of the game the first time.
It's up to Matrix, though, so if he doesn't reply to the thread quick enough for you, you may want to PM him for an answer.
I think that since this is the first GOTM for Civ3 and will have many new first time players, many exceptions might be made.