stripping aqueous flat clear

Try wet sanding it with water and a polishing stick. Use no pressure on the stick, just let it glide over the surface to knock down the high spots that are giving you the hazy look. Work in small sections, drying and checking your progress as you go.

I use this method to "gloss up" areas on flat painted surfaces to accept decals in lieu of glossing, decaling, flattening again. Whats the point of using a flat paint in the first place if you are going to gloss it over anyway? 

There's really no easy way to remove the flat coat without affecting the colour coats underneath.

One thing you might try if the haze isn't too bad is to hit it with a clear gloss coat. This has been suggested a few times previously and has been said to work in a number of cases.

What sort of aqueous flat clear did you use?