PERM application with new employer

[deepthis]

Hello,

I changed employers in march 2018 from A to B. I have a approved i140 from Employer A (old employer ) . My current employer has not yet started the PERM application process yet. 

My h1b is up for extension in March 2020. Can someone please confirm if I need an approved i140 with my current employer B or can I use my old i140 when submitting for extension in march next year. 

Thank you all in advance. 

Deepti