PERM labor certification expired, new PERM filed - Priority Date


My employer filed PERM in May 2014 and it was approved in Sep 2014. I-140 application was sent to USCIS in Mar 2015 for filing. Unfortunately, we have not received the I-140 filing receipt. Then my employer again filed the PERM in July, 2015 and waiting for the approval. In this scenario, what would be my priority date? Do I lose the my first PERM filing priority date that was originally May 2014?

Appreciate your help !

Thank You.