In my Vampire: the Masquerade game all stat increasing are necessitated by in-game actions to improve the related stat. Other than Vicissitude, what in-game actions would be appropriate to facilitate the permanent increase of the Appearance attribute?
Appearance isn't just the raw materials that come from one's looks; it's also the way one uses first impressions and style to their best effect. Some potential in-game acts that might suggest a rise in Appearance: learning to use makeup to better flatter oneself; buying a new wardrobe (or manipulating fashion trends to make the style you already favor become the in, hot thing.); assuming postures and behaviors that show off your best attributes. These might also facilitate buying other Abilities and Attributes to complement them, just as an increase in Athletics might accompany raising Strength or Dexterity.