Re-priming?

[Traveller1865]

If a sprue with figures are primed, but with paint chiping, do I need to remove all rests of the primer or can I spray a new layer on top?

[Bluefalchion]

I would think it would depend on the level of detail of the figure. You do not want a layer of primer so thick that you obscure the fine details. I have painted some figures with a gap in the primer and it turned out okay.

So I guess the answer is it depends.

[Bramble15]

Is it possible to brush a little primer onto the affected area and start from there? I agree with Bluefalchion, you don't really want to add multiple layers of primer if you don't have to.
Perhaps a light covering with PVA/Elmers glue to seal and prepare the surface for paint.

[Bluefalchion]

Agree about the PVA glue. Marvin turned me on to that one...

[Zed1]

If the primer is already chipping away, I would always clear it all off with a hard brush in a warm bath of water.
Too dangerous that the rest chips off later on and damages your work.