From October 2, 2017, those wishing to extend an EB visa for either six- or 12-months will be required to present the following documents at the time of application:

Employment letter (original) or
Work permit card issued by the ministry of labor (copy) or,
Business License or Patent certificate (copy) (for business owner) or,
Employment Contract valid until the latest date of extension or,
Relevant document stating the necessary of temporary stay in the Kingdom

It leaves untouched first EB visa and is applicable only for extensions.