If a learner has already commenced learning a course or resource they need to complete before you had an opportunity to assign it to them, you can add a due date from the Manage page for that course or resource.
Select Self directed from the left navigation, followed by the status of the learner's progress against the course: Not Started, In Progress, or Completed.
From Self directed > Not Started, Self directed > In Progress, and Self directed > Completed, you will see a checkbox to the left of each learner within the table. You can select one, some, or all of the learners in the table. An action bar will appear at the bottom of the page, with the button: Add assignment.
Selecting this button will pop up a window, containing the ability for you to specify a due date for the selected learners.
Add a due date and select the button Add assignment to confirm.
The selected learners will receive an email notification, informing them of the date by which they need to complete that learning. If the learner's completed learning is outside of your current compliance period, you will then need to reassign the learner to the course or resource.