changing lip color in after effects

Sometimes, you forget to put lipstick on or do not have a proper shade of lipstick but don’t worry about this because Photoshop has made it easier for you to change or fix your lip color in images. You can change lip color in Photoshop. Learn at: https://cutoutimagemedia.com/change-lip-color-in-photoshop/

If you added the lipstick smudge to the mirror it is already on a separate layer, if it is in the shot you'll need to separate the lipstick smudge from the background. This typically involves motion tracking, masking, and creating a procedural matte. 

Once you get the smudge on a separate layer you can animate color corrections or fills. There is not much to it after you get the smudge on a separate layer. Show us a screenshot or the footage and give us some more details about the shot and we can give you some suggestions that will point you to an efficient workflow.

This one:

Would require a fair amount of work. Probably a couple of hours.

This one:

Would be a lot easier.

If you have not shot the footage yet careful planning, lighting, and attention paid to putting things in the scene that will make it easier to pull a matte or do some roto will save you a lot of time. You can't expect to just grab a camera and shoot something, then isolate elements and create the visual effects you want. 

Seeing a reference frame clearly would help, but how 'bout basic masking and applying an effect like Hue/ Saturation?

Mylenium