Use the Update One-Line Diagram command to update your one-line diagram to reflect any changes to your design.
Generally, the one-line diagram is updated automatically as you modify your design. Use this command if changes were made on a different drawing in the project, or when you need to be sure the one-line diagram reflects the latest changes.
To update the one-line diagram, go to
Ribbon: DM Electrical->One-Line Diagram-> 
Update One-Line Diagram
Pulldown Menu: DM Electrical->One-Line Diagram->Update
This command will update:
| • | all of the labels on the one-line diagram |
| • | any connections between devices, removing feeders that no longer exist and adding ones that are missing |
| • | all of the layers, colors, and text styles to match your current customization settings |