Ya when making something originally with rbg, when you change it to cmyk the colors will be off, its trying to match the closest cmyk to the rbg color. CMYK color pallet is really limited compared to rbg. Its usually a good idea in the future, if your going to be printing it out, start out with cmyk, if your not printing and is going on the web then rbg is fine. You can try to change the hue/sat, vibrance or exposure.
Have you decided where your printing it out at???
Another option, might be an easier one the redoing it all........The costco out where i live can print RBG files. Some Printers now a days can print RBG colors. I would find that out 1st, if they use an rbg printer. THen you would only need to get the printer profile for their printers, so u can set that profile up in ps to see how the print will look. Then adjust it if its to light or dark.