Impact on I-485 application due to job change

[VivekShan]

Hi all,

This is my situation

1. Priority date - November 25th 2009 EB2
2. I-140 approved (it was approved sometime in 2011)
3. EAD/AP approved and is being renewed since 2012
4. I-485 application is pending and Initial interview also done last year.

Below is my question

If i change my job and/or move from an engineer title to a manager title, does the entire process starting from Perm/labor/I-140 application need to be started keeping the same priority date or is it enough if we just file an AC21 (amendment)  and not have to go through the entire process all over again? 

Any insights on this will be very helpful.

Thanks,

Vivek