Replacing the cables on your Enviolo CVT isn't terribly difficult, but it can be a bit tricky to load the cables into the shifter. Your bike uses two standard shift cables, available at any bike store for a few dollars or from any number of online vendors.
Please review all of these videos before beginning.
This video shows the replacement of the cables themselves. You will first need to remove the cable end hardware from the old cables by loosening the set screw and sliding it off the cable. That step is not shown here, but will make since after you see the second video:
How to replace the shifter cables
This video shows the proper measurement and installation of the cable end hardware:
How to set the cable length for manual hub Interfaces
This video covers the adjustment of the hub itself to ensure that you are getting your full range of shifting. This isn't necessary in most cases, but may be useful so we are including it here:
How to reset an enviolo hub to full overdrive