It seems that upgrading my existing MCPD SharePoint Developer 2010 to MCPD SharePoint 2013, I need to take:
The two exams are
2. 70-493 Upgrade your MCPD: SharePoint Developer 2010 to MCSD: SharePoint Apps
But 70-493 has not been out yet, so I will focus on 480 for the moment now.
Check here for more details: