Evening all

I have recently painted a rear valance, left the clear a few days to harden off, took it out in the sunlight next to the car and as you can see, the colour match is fuckin shite.



So my question is, how do I need to prepare the lacquered surface before applying more base coat. Do I need to sand right back to the primer, or can I key the surface of the lacquer and paint over the top? Although I want to do it properly, I would rather not have to sand back by hand a complete rear valance!

Thanks in advance

Rich