Apply to the court for subsequent cosmetic expenses appraisal or go to the judicial institution for appraisal first.
According to the second paragraph of Article 19 of the Judicial Interpretation of the Supreme People's Court on Several Issues Concerning the Application of Laws in Handling Personal Injury Cases: "However, the expenses that must be incurred according to medical certificates or expert conclusions can be compensated together with the medical expenses that have already occurred". You can evaluate the cost and get compensation in the lawsuit.