H1Blayoff
You need the following;
1. Check/money order of $120
2. Copy of your I-94 (front and back), if available or you can write your arrival and departure dates on a plane white paper and submit ( I did the later because my I-94 is expired and my lawyer suggested me to do this).
3. Copy of Your previous EAD (front and back)
4. 2 photographs (INS style)
5. Copy of your I-485 receipt notice or proff that your AOS is pending.
Lastly, include the top portion of the letter through which you received your first EAD.
Requirement of item number 5 is always a dispute. Some argue that the A# is itself a proof. But, why take risk. Better send it.
Good luck
Bob