i had to change my apple ID now how do I update icloud without deleting all cloud data on the computer?

My provider is terminating email service so I had to change my apple ID. I did that in iTunes but now my icloud on my PC wants me to sign in under my old id, I don't see a way to update to the new ID without deleting all cloud data on the PC. Is there another way so I don't have to resync everything from the cloud?