Live updates from Illustrator to After Effects

Here's my workflow that will solve that problem. 

1. Rename the folder in the Project Panel that was originally created for the layers when you imported the AI file as a composition
2. Rename the main comp created when you originally imported the AI file as a composition
3. Open the original AI file
4. Add the new layers
5. Save the file
6. Return to After Effects and import the same file as a composition again
7. Open the new footage folder created when you imported the updated Illustrator file as a comp
8. Drag the new layers into the Renamed Footage folder
9. Open the newly created comp, select all of the new layers, then copy them (Ctrl/Cmnd + C)
10. Return to your original comp (the one you renamed) and paste (Ctrl/Cmnd + v), then arrange the layers in the proper order
11. Return to the Project Panel and delete the newly created comp with all the layers and the footage folder for that comp

There you go. Your AE Project is now updated, the new layers are in place, and you are ready to continue editing. The whole process of updating the original comp and footage folder should take you less than five minutes. 

The same workflow works for Photoshop files imported as compositions. I probably update a project that way about two or three times a month because clients request additional graphics or animations, and I charge for the changes if the work goes beyond the original contract.