You must upgrade to the supported Junos Space Network Management Platform Release before you upgrade the Security Director, Log Director, and Security Director Logging and Reporting modules. As per my understanding, you need not import the security director again. Just follow the steps mentioned in our documentation and it should be good.
I am pasting below a link to upgrade guide for security director:
As per my understanding, there won't be changes to the SRX device either than the OS during its upgrade. So, you will not have to worry about the existing configuration already managed by the Security Director. Also, the management of Junos software is not directly handled via Security Director.
Just before you proceed, refer to the below KB. It might be useful:
You should not need to reimport the SRX however, when you upgrade your SRX you may see that there is a DMI schema upgrade needed. The new schema will be needed to configure new features not previously covered in the old schema.