I understand your situation, and it's important to seek legal help in such instances to ensure justice is served.
Under Saudi Arabian laws, there are a few possible steps you can take to reinstate your innocence and restore your reputation. The process would generally involve appealing your case or filing for a retrial; however, I am unable to provide specific legal laws in such cases as every case varies significantly.
Since you have completed your sentence, it's important to know whether you have already appealed your case or not, since the Saudi Arabian judicial system allows defendants the right to appeal.
1. Appeal (Article 173 - 188, Law of Criminal Procedure):
The Law of Criminal Procedure in Saudi Arabia allows for the possibility of appeal. Under the relevant rules, one must first file an appeal with the Court of Appeal within 30 days of the pronouncement of the judgment. The appeal must contain a description of the judgment, reasons for the appeal, and desired outcome. This could be an option if you were unjustly deemed liable in the first instance and you believe there is more proof to show your innocence.
2. Petition for retrial (Article 229, Law of Criminal Procedure):
According to Article 229, a retrial may be asked if there appears to be evidence which may result in the acquittal of the accused, which was not presented in the original trial due to circumstances beyond control.
Please note, this information is general in nature, and legal advice must be sought in relation to your specific situation. It is advisable to consult with a local Saudi attorney who specializes in criminal law and can guide you with their expertise. They would be aware of the exact procedures, intricacies of the law, and know how to navigate the system for an efficient resolution. This is important because the laws are subject to interpretation and change, and a seasoned professional would be most updated about it.
Remember, it's your fundamental right to seek justice and you should exercise it under all circumstances.