A fresh appeal to help solve Charlene Downes' murder has been aired BBC's Crimewatch Roadshow.
The tragic 14-year-old's mother and sister relived Charlene's last movements around the resort as they asked for new potential witnesses to share information.
Charlene's mother Karen Downes said: "I was at work giving out leaflets. It was about 6.45pm and I saw Charlene and her sister Rebecca coming up Church Street.
"Rebecca said she was going home but Charlene said she wanted to meet her friends. She said 'love you mum,' I said 'love you too'. She walked off in the direction of the Winter Gardens and I never saw her again.
"She's missed out on everything - all her life. She's left a big hole in everybody's hearts and minds."
Police are now asking anyone who lived or worked in or around Abingdon Street -where Charlene was last seen - to come forward.
Detective inspector Andrew Webster said: "We're determined to find out what happened to Charlene and part of that is trying to trace her last movements.
"She was last seen at around 10.30pm on Nov 1 2003, in an alleyway just off Abingdon Street. We want to identify people who lived and worked in that area.
"We have established she was sexually exploited. We would like to speak to other victims of sexual exploitation around that time. They may hold bits of information that may help us to take this forward."
Charlene's sister Rebecca said: "There isn't a day that goes by where we don't think about her and miss her.
"Just come forward. It's never to late, we're just a family and we need answers.
Her mother added: "Please give us some closure and peace and give Charlene some justice."
A £100,000 reward has been offered for information that leads to the discovery of Charlene's body or the conviction of her killer.