After workshops on functionality and data, you will have a much more detailed view on the scope. Use this information to update the High Level Scope to the Intermediate Scope.
If during the workshops, additional scope becomes evident, treat it as a scope variation. It should go through the change control process. Sometimes it is difficult to decide if something is additional, or was part of the originally declared scope. If it means additional time and cost, treat it as a variation.
To produce the new document, take a copy of the High Level Scope, and change the name to Intermediate Scope. Review each section to determine what might have changed, or what has evolved. It is important to keep the High Level Scope document for reasons of traceability.