Can you reassign or change your character's attributes and abilities(respec) more than once in Diablo 2?

I know Akara will reset your stats and skills for you in the first area once, but are you able to do it again later in the game on a higher, more difficult setting?

Only once per difficulty, after that if you fuse 3 essences (dropped from the Act bosses in hell) in the Cube in Act 2 you can get more.

To add to Noctrine's answer, actually there are 4 essences that must be cubed (red, yellow, green, blue). Baal, Mephisto, and Diablo each drop a different essence, and Duriel and Andariel both drop the same fourth essence. Cubing the essences gives you a Token of Absolution, which can be right-clicked to respec.