Change a question's scoring and the answers already graded against the old version now catch up on their own. PATCH /exams/{id}/questions/{questionId} re-grades a question's automatically graded answers in the background whenever its scoring changes (toggling excludeFromGrading on its own doesn't count).
To re-apply new AI grading instructions across a whole exam, the new POST /exams/{id}/sessions/regrade-ai queues a re-grade of every AI-graded answer a teacher hasn't touched since. Both leave manual grades and answers with teacher feedback alone, and answers report a gradingStatus of auto-grading-pending while the re-grade runs. See the grading docs for the full flow.