The 40-year-old New York woman was paroled in May after serving nearly 15 years in prison.
But a court reincarcerated Berenson in August on a technicality and she took along her now 18-month-old son.
The same judge who initially paroled Berenson reinstated it Friday.
Berenson cannot leave Peru until her 20-year sentence ends - unless Peru's president commutes it.
Prisons spokeswoman Janet Sanchez said Saturday that the agency was still awaiting the documents needed to release her.