Hello!
Basically you have two options - one is to take the coat down, and put on a new layer, and the second would be to try to soak those white places with something to make the layer transparent again - I was once able to save my figs thet turned white after putting a flat clear coat on them. To see if it has a chance of success, try brushing on some mild solvent - like Mr Colour Thinner from Gunze, or Humbrol paint thinner - if the flat clear turns translucent but gets white again after the thinner dries, the places can be saved - just take a clear varnish, thin it 50 - 50 and brush it on. If the thinner itself doesn't help, then you have to take the coat down and put on a new one. Hope it helps, good luck with your project and have a nice day
Paweł