You'll have to build a whole new windows instance using Windows 11 for ARM.  The existing virtual machine won't work - Intel (x86) vs ARM is like gasoline vs diesel - you can't put one in an engine built for the other.

The good news is that with the Unofficial guide's new instructions, it's not terrible to get the installation media.  Your windows product key from your previous VM may very well activate Windows 11 (give it a try).  Even better is that built into windows 11 is a rosetta like layer that will let you run x86 software inside the windows 11 arm guest.  But you will have to reinstall all that software.