The Calder High School pupil was 13 when she went missing in Hebden Bridge and would have celebrated her 30th birthday this year.
Her body was found in the Rochdale Canal five months after she vanished - and her killer has never been caught.
Detective Superintendent Colin Prime, of West Yorkshire Police’s major investigation review team, said: “I firmly believe someone, somewhere, could hold vital information that would lead us to the killer.
“Although 17 years has passed, we continue to seek the vital pieces of information that will bring closure to the investigation and for Lindsay’s family.”
Lindsay disappeared on Monday November 7, 1994, after leaving her home in Cambridge Street at around 10pm to visit the Spar shop in Crown Street.
On her way she called at the Trades Club, Holme Street, where her mum was drinking with a friend.
CCTV footage from the shop showed that Lindsay paid for a box of cereal at 10.22pm. She never returned home.
Her body was found in the Rochdale Canal on Wednesday April 12, 1995, about a mile upstream from Hebden Bridge town centre. She had been strangled.
Police investigating her murder have spoken to thousands of people and taken hundreds of statements over the years. Now they are appealing for fresh information.
Det Supt Prime said: “It may be someone has harboured a suspicion all these years. With the passage of time, someone who was unable to come forward and speak to us 17 years ago might be in a position to do so now. I would strongly urge them to get in touch.”
Call police on 0845 6060606 or Crimestoppers, anonymously, on 0800 555111.