Dear Haider, that information is not necessary to fill in even if you are appearing NEET PG for the 2nd time. The only possible way to retrieve the previous examination details are to go to the Registered Email and check for the communication mail from NBE regarding your admit card or application number. But this information is irrelevant when you are appearing for NEET PG again. The form might ask you if you are appearing for the first time or if you have appeared for this exam in the past. You will answer accordingly. This is just for statistics purpose and nothing else.