Why not just hide (or make available but not visible) the "text box" and add the "page" in addition?
Thus, students who have already marked the "text box" won't be affected and the new students will simply click on the "page" resource. After some time you can delete the "text" resource.
Thus, students who have already marked the "text box" won't be affected and the new students will simply click on the "page" resource. After some time you can delete the "text" resource.