In 15.7 and above you will see that the limit is 500
Environment
Release : 15.6.1
Component : CA PPM SAAS STUDIO
Resolution
In 15.6.1, the workaround can be to remove the api alias for the attribute you don't want to add in the blueprint and ensure you are under 200 attribute.
Also, plan to upgrade to the latest supported release (currently 15.8.1) where we have enhanced the limit to 500 (change made starting in 15.7)