@MarioKnimer welcome to the KNIME forum. You will not loose all your workflows. Although it is always advised to have a solid backup strategy in place just in case something goes wrong.
Your workflows should ‘live’ in a different place than your installation. So you could switch out the KNIME program at any time and simply tell the ‘new’ KNIME program to use your current workflow path.
This guide is long and technical but it should explain (almost) everything about KNIME and paths and where is what (this might come in handy at several time in the future):
https://docs.knime.com/latest/analytics_platform_file_handling_guide/index.html
So you could just do a fresh installation of KNIME at any time in a new folder. And then the existing KNIME has an update function built in that should work within major releases. More on updates here: