The 20-year-old's future at London Road was put in doubt after he and three team-mates were fined and transfer-listed following a breach of club discipline.
However, following a successful loan spell at Portsmouth, the winger has played a pivotal role in their current four-game unbeaten run, netting in Tuesday night's 5-1 thumping of Millwall.
The former Wolves youngster has told Sky Sports that he has learnt from his mistakes and is determined to atone for his error.
He said: "If I'm honest at the time I did feel that my time was up at Peterborough, but having come back from Portsmouth I sat down with the manager and we managed to settle our differences so that we could get on with the football side of things.
"I've been involved with Peterborough since I was 17, having helped the club gain promotion whilst on loan and then I almost joined permanently last season before finally arriving last summer.
"I've always been involved and it would have been sad to depart in the way that things were earlier this season.
"I'm happy that that wasn't the case and I can look to repay the fans by my performances on the pitch.
"The incident obviously hasn't helped, but it was definitely a learning curve for me."
Mendez-Laing added: "I'm grateful to have been given a second chance by Peterborough and hopefully I can make the most of it.
"I feel more confident than ever now and having gone through all the different emotions that I have felt this year I've got more hunger in my belly to do well.
"I just want to focus on football, gain more experience in the Championship and ultimately help keep Peterborough up and then we can regroup for next season."