You can specify whether or not you want to retain the connection with the 2D data in Element info. Select the placed file and choose Element > Element info. The following dialog box appears:

On opening the dialog you will see information on the file name, format and status. You cannot select the OK button. Clicking Cancel exits the dialog box without any changes being made. If you have executed the Update now command, you can confirm this by clicking OK. The Cancel button is no longer active. Clicking Break link automatically closes the dialog box.

If you click this button, the file will immediately be updated.

Clicking this button breaks the link to the original file. The data is imported into the current illustration. The link cannot be restored.