Restat will change your character from level 3 to level 1, removing all practices and stats allowing you to try for better stats. As upon reaching level 3 all characters will be given a set of stats, these being Strength, Intelligence, Willpower, Dexterity and Constitution.
Anecdotal evidence indicates restatting is possible as high as level 4. Further testing is needed to determine the maximum level for this command.
In Game Description