To update an attendee's completion date for a session in LCvista, follow these steps:

1. Click on Manage Attendees.
2. Use the search function to find the specific program ID and session ID you need to update.
3. Locate the attendee(s) whose completion date requires adjustment.
4. From the Actions menu, select the option to reprocess the attendee with either full or custom credit. This action will enable you to update the completion date.

By following these steps, you can efficiently update the completion dates for attendees, ensuring their records are accurately maintained.