You might also check to be sure the game is set to update in steam. this is the default setting, but to check go to your games library, right click on planet coaster, select properties. Click the updates tab and the first setting gives you options for keeping the game up to date.
Mine currently says 1.1.1.37699 and I know this includes the winter update (1.1.0.) as well as the next day "patch" (1.1.1)