I have created a feature, a publishing site, in Visual Studio to MOSS - this feature contains a masterpage, some page-templates, some site columns (grouped to match each page-template) and som custom list templates etc. I have also created a site collection, some sites and pages based on my feature.
Now I have upgraded the code in my feature - I wanted a ListInstance to be created based on my custom list template. When I have upgraded my SharePoint (using WSPBuilder), the ListInstance and default data are visible if I create a new site collection, but existing site collection does not get the ListInstance and data. Is there anything I can do to update existing site collections to contain the ListInstance when upgrading?