Back in 2014 PS4 lead architect Mark Cerny suggested that Knack might have a sequel in the near future.
Nothing much has been revealed about the possible sequel until now. According to a LinkedIn profile for Mindy Liang a 3D animator it seems that she might be part of the team working on Knack 2. The information on her profile stated that she has been working on the game since May 2015. As is to be expected the information has since been deleted.
Below is the launch trailer for the original Knack.