It looks to me like Cubase retrieves the patches from the plugin only once, when the plugin is created. However, I produce a VST instrument plugin (VST 2 only!) that can change the internal patch list any time. Users would be happy if these changes could be transmitted to the patch list in Cubase. Can it be done using a suitable VST 2 command?
This can be done with the VST3 SDK (see program lists in the documentation). Don’t know if this was possible with a VST 2 plugin.