Hi there, @fcweesp.nl 
Thank you so much for the feedback!
The sitemap training is available only during the initial widget setup (in the “Create AI Agent” step):
When you enter your website URL, the widget automatically pulls all your website’s pages and uses this information as its knowledge base.
However, if you created the widget before the update or skipped this step during the initial setup and added the information manually, the sitemap training won’t be available in these cases.
The only option is to create a new widget now or duplicate the widget and train it from scratch. I am really sorry!
We understand that being able to train with a sitemap beyond the initial setup would be really helpful.
We’ve added this idea to our Wishlist, so feel free to upvote it if you’d like to see it released 
- Train with sitemap beyond initial setup