Rafael Benitez has guided the North-East outfit back to the top flight at the first time of asking, and they secured progression with a comfortable 4-1 victory over Preston North End at St James' Park.
Two defeats and a draw has seen the club slip from top spot to second, but they still have a chance of winning the title as they sit four points behind Brighton & Hove Albion with two games left to play.
"It's been a tough season and today it's paid off," Lascelles told Sky Sports News. "The atmosphere has been unbelievable - the fans have stuck behind us.
"The main aim was to get back into the Premier League but of course it would be nice to win the title. We'll see how the next game goes."
The Magpies, who have won 27 of their 44 games, losing 10 and drawing seven, will face Cardiff City and Barnsley in their final games of the campaign.