You can keep your previous installation or do a backup.
Devserver doesn't install anything on your system or in the registry. So, if you want to remove your previous installation you can just remove the folder (that's why it's portable and easy to use) or back it up somewhere else.
Devserver 17 in another folder (the default one proposed, for example) or on a portable drive (USB drive, hard drive, memory card...) .
If you put your files in "Portable Directory" (<your-installation-folder>\eds-www for example), copy and paste them in your new "Portable Directory". If you have created "Working Directories" don't touch your files, you just have to recreate your "Working Directories" by clicking on add directory.
In your previous installation, open "PhpMyAdmin" and click on Export. In your new installation, open "PhpMyAdmin" and click on Import.
Download compatible components and modules and install them.