The Home Office allows some categories to move into the Tier 2 General. You can switch in to the intra-company transfer category if have permission to stay as a work permit holder, as long as that permission was given to you as an intra-company transferee and you are still working for the same employer when you were given that permission.

If you are not in this category, you must leave the United Kingdom and apply with a new application at your local entry clearance post.