The restoring booster is an injection Artemis Fowl (II) gave to a drunken Faily Healer at the beginning of Artemis Fowl (Novel), which comined with a vial of spring water was used to bargain for a look at The Book.
He describes it as "a little shot of man-made magic. A virus that feeds on alcohol, mixed with a growth agent. It will flush every drop of rice wine from your body, remove the dependance, and even bolster your failing liver." He also tells her that it will be a painful experience.
We later find out that the restoring booster was mixed with an amnesiac which caused the sprite to forget the preceding week.