Created by Isobel and voiced by Dawn French, "School of Cornish" will give visitors to the county the means to tell people they are excited (yntanys) or puzzled (kemyskys), or that something is a disaster (terosa).
Last year’s ad is also returning to TV, and will be supported by press and digital out of home.
Charlotte Hambling, UK head of marketing at Kelly’s owner R&R Ice Cream, said last year’s campaign had helped the brand grow sales by 25% (according to Nielsen, year to April 2017).
"Using the Cornish language gave us remarkable cut through with our consumers so it made sense for us to build on this and continue to celebrate Cornish culture," Hambling said.
"The series of films Isobel has created and the School of Cornish platform do exactly this – showing off the local area and culture to great effect."
The spot was created by Ben Stump and Simon Findlater at Isobel and directed by Mark Leary through Swerve Presents. The7stars handles media for Kelly's of Cornwall.
Jamie Williams, partner at Isobel, added: "The Cornish way of life is unlike any other. Some say it’s a laid back attitude. Some say it’s not taking life too seriously.
"Whatever it is, it’s certainly unique and we hope that the campaign gives consumers across the country another taste of what it really means to be Cornish."