Shoaib was reprimanded for breaching the Players' Code of Conduct on April 1 and was banned from playing domestic and international cricket for five years.
Four days later the Rawalpindi-born paceman appealed against the ban and the PCB chairman Dr Nasim Ashraf subsequently formed a three-member Appellate Tribunal, headed by Justice Aftab Furrukh, to hear his case.
Shoaib, 32, was advised to file a fresh appeal by April 21, which he did on Monday.
M Ali Lashari, a member of Shoaib's legal team, filed the additional appeal, challenging some of the charges levelled by the PCB disciplinary committee.
The fresh appeal also urges the tribunal to revoke the five-year ban.
The panel held its first meeting last week and ordered the PCB secretariat to provide copies of some of the documents required by Shoaib.
The tribunal, which has Salman Taseer and Haseeb Ahsan as its two other members, was scheduled to begin its hearing from April 26, but proceedings have been put back two days because of Ahsan's personal engagements.
Shoaib had previously lashed out at the PCB, saying he was being "victimised".
He was already on two years' probation for hitting Mohammad Asif with a bat before the start of the World Twenty20 in South Africa in 2007, which attracted a fine of 3.4 million rupees (US dollars 52,000) and a 13-match ban.
The controversial paceman has signed for the Kolkata Knight Riders in the Indian Premier League after the club's owner and Bollywood star Sharukh Khan bid US dollars 425,000 for his services.