Once you lapse an account, you lose your original id which is still stored on the database, and have to use a new one. You can ask HTC admin by mailing them to transfer your old ID to the new account once they have verified that you are the same person.

You lose all perks you may have earned of course.!
AFAIK my old temporary account was under "Spiff" and my new one "Spiffy", as I'm known generally by either id I didn't bother to get it transferred back, but probably the old id "Spiff" is still locked into the database, at least it was "already taken" when i rejoined.
There is probably a time limit on how long old "ids" are locked for in AH, historically in AW some could be "locked" for "ever" by a Head Game Operator for game "ids" belonging to the "Gods" of AW

, but normal ids could be transferred by staff after ascertaining they were the same "persona". HTC admin or Skuzzy can fix this in AH for anyone providing that the old name is not taken and they can prove they are the same person.