i recently went through refinishing a painted hull.  similar to you i had some chips that i wanted to deal with.

i did the following before recoating the entire boat.

- i would lightly sand the area around the chip(s) with wet 400 sandpaper.

- clean the area with paint thinner

- use a small brush to dab fresh paint into the chip and slightly/lightly onto the surrounding area (brushing towards the chip)

let dry (at least 24 hours when warm - check the paint for recommended dry times) and then repeat above until i had a level surface with a uniform color.

i was then able to refresh the boat with only one fresh coat becuase the undercoat was consistent (note...i was refinishing with the same color).

i will typically deal with chips and scratches and even large repairs at the end of the season without redoing the entire boat.  unless inspected from very close......the briteside enamels are very consistent and if applied carefully, you can do a part without having to re-do the entire boat and most people will not be able to tell unless they really exaine it up close and carefully.