This YouTube video will introduce the procedure for first-time application, renewal, and replacement of damaged or lost Tunisian passport with the Tunisian Embassy in Beijing.
Passport application forms (make sure to fill them in in both Arabic and French):
Note: If your occupation changed from a student (at the time of getting your ID card) to work, then you can still submit your passport renewal application, but you will need to update your national ID card when you go to Tunisia)
The procedure for updating the data on your national ID card is available here (in Arabic).
Form to return the old passport:
You should receive a letter of receipt of the new passport from the embassy as follows: