In a high-powered blender, combine the pineapple juice, vanilla ice cream, frozen pineapple, lime juice and salt. Blend on medium-high speed, stopping to push the pineapple chunks down into the blender as needed. Transfer to a bowl; cover and freeze for 30 minutes. Scoop and serve. Alternatively, transfer to a piping bag fitted with a large star tip and pipe into small serving bowls. (This method will make it look like it came out of a soft serve machine.)