Don't worry - just install on top of the previous version. It will report all the add-ons (CUDA toolkit, database server, QT etc) as installed, and upgrade just the main program while keeping your settings.
Is there a way to get Resolve to use my CUDA compliant card on my laptop - keep getting a message that I need such a card (which I have on the laptop) despite forcing the Nvideo 640M card usage in the Nvidia settings when launching the program.