You can export a knowledgebase by using the Backup wizard in the  Admin Console. The Backup wizard creates an export file of the KB that can be used just like regular knowledgebase export files.

1. In the admin console, navigate to Setup > Backup.
2. Select which knowledgebase to export, then press Run Backup Now.

You can also set a schedule for automatic backups by editing the backup and selecting the Frequency tab. Each backup creates a new export file; old files are overwritten when they become older than the backup expiration date set in the Backup wizard.