The Codex Repetitae Praelectionis was the second edition of the Codex Justinianus (Code of Justinian). It came into force by the constitution Cordi on 16 November 534 and was necessary due to Justinian's own legislative activity in creating new laws since the original code was issued in 529. It consists of 12 books and was written mainly in Latin.
References
Codex Repetitae Praelectionis Wikipedia(Text) CC BY-SA