is PERM required when changing from EB3 to EB2

[SeethaS 0]

Hello, 

My spouse's GC was filed under EB3, six years back. His i140 was approved. 

Since, EB3 is retrogressed to 2012. meanwhile, we has promoted multiple times, and moved to management role.

My spouse is now discussing with his employer for change of category possibly to EB1(2). 

if at all the employer agrees, please clarify the below

1. is PERM required to file again to do category change?

2. what is the criteria to meet to change from EB3 to EB1?