Peter was not saved by our definition when he denied Jesus. Nobody was born again until the Resurrection. We were are raised up together with Him at that moment. The whole body of Christ, past, present, and future were raised up at that instant.
We can see that nobody was born again during the ministry of Jesus by a number of proof texts.
First there is the fact that Jesus called Peter satan.
"Get behind me satan..."
Peter was not yet saved or born again at that time.
Then in John 8 we see a prolonged conversation with those who John called believers. If the new birth was available at that time, they would have been born again. Yet we see Jesus tell these believers that they were children of the devil. Certainly not born again.
John 8
30 As he spake these words, many believed on him.
31 Then said Jesus to those Jews which believed on him, If ye continue in my word, then are ye my disciples indeed;
32 And ye shall know the truth, and the truth shall make you free.
33 They answered him, We be Abraham's seed, and were never in bondage to any man: how sayest thou, Ye shall be made free?
34 Jesus answered them (those Jews which believed on him), Verily, verily, I say unto you, Whosoever committeth sin is the servant of sin.
35 And the servant abideth not in the house for ever: but the Son abideth ever.
36 If the Son therefore shall make you free, ye shall be free indeed.
37 I know that ye are Abraham's seed; but ye seek to kill me, because my word hath no place in you.
38 I speak that which I have seen with my Father: and ye do that which ye have seen with your father.
39 They answered and said unto him, Abraham is our father. Jesus saith unto them, If ye were Abraham's children, ye would do the works of Abraham.
40 But now ye seek to kill me, a man that hath told you the truth, which I have heard of God: this did not Abraham.
41 Ye do the deeds of your father. Then said they to him, We be not born of fornication; we have one Father, even God.
42 Jesus said unto them (those Jews which believed on him), If God were your Father, ye would love me: for I proceeded forth and came from God; neither came I of myself, but he sent me.
43 Why do ye not understand my speech? even because ye cannot hear my word.
44 Ye (those Jews which believed on him)are of your father the devil, and the lusts of your father ye will do. He was a murderer from the beginning, and abode not in the truth, because there is no truth in him. When he speaketh a lie, he speaketh of his own: for he is a liar, and the father of it.
Jesus clearly calls these pre-Resurrection believers children of the devil both in identity and nature. They were not born again or saved by our definition...
Since he was not saved by our definition... he could not lose his salvation. Hence I cannot answer your poll.
The answer is he did not lose what he did not have.