Change CMYK values

Hi Everyone 

I need to change artwork to a specific CMYK

However there are 40+ layers

If I change the CMYK to eg. C70 M80 Y0 K0, its one big blob of solid colour

How can I change the colours and keep each layer a different shade??

I have attached an example and need the overall colour to be C0 M90 Y20 K0, with gradients