The grace to repent , not just on behalf of oneself but also on behalf of others, trusting in the goodness of God and thus asking for mercy , is a gift of The Spirit ; thus, it is likely that St.Peter did so to the utmost, after the Lord appears to the disciples and breathes on them .
The Lord had promised to Peter , on a previous fishing expedition, how he was going to make him a fisher of men , in answer to his acknowledgement of being a sinful man …and may be The Spirit stirred the heart of Peter to sense that , that promise was going to be fulfilled , in spite of his sin of denying The Lord, thus his decision to go fishing !
Thus, not catching any fish that night may not have disappointed him …but likely , only helped to remind him of the previous time , when the promise was made !
Having heard interpretations on how the Apostles following Peter that night was a temptation, seems the liklelihood of the occasion being more in line with the promptings of The Spirit is also good to consider , esp. from the point of the role of repentance as a precious gift ; St.Thomas is mentioned in that episode , right after Peter ; he too could have repented well , for leaving The Lord , like the others !
Interestingly, the Divine Mercy Sunday coincides now , with St.Thomas Sunday of Octave of Easter !
This grace of repentanace and the related gratitude could be what made Mary Magdalene also to have the privilege of being witness to The Resurrection , even before the disciples !
Tomorrow being All Souls Day, good day to repent on behalf of all in the family and many others, asking for mercy !
Such an attitude may be what could also foster unity in The Church - those who have fallen away from The Church , repenting on behalf of all those persons /Popes etc : who they have heard played a part , as the cause for the divisions/reformation and Catholics doing so , on behalf of those who took the misguided efforts , to bring about the divisions !
The prayers for holy souls, such as this one -
catholicspot.com/purgatory.htm is possibly another way of doing same !