v3.canjs.com is hosted on GitHub pages from the canjs/3.x#gh-pages branch and generated from the canjs/canjs#3.x-legacy branch. To generate and push a new version of the website, verify you have push access to those branches. Then get all latest changes via:

git checkout 3.x-legacy
git fetch --all && git rebase
npm cache clean
rm -rf node_modules

We also have to delete the local gh-pages branch:

git branch -D gh-pages

Then run

make

This will generate and publish a new version of the website.