Delete the save file?
When you uninstall, it probably doesn't delete that (just a guess, as many games don't).
C:/Users/[Computer_user_name]/AppData/Local/ShopSim/Saved
I just deleted the whole Saved folder and it worked pretty well. Another option, which I haven't tried, is that in the new 71 update you can start a new game from the menu. I'd personally try manually deleting the save file first.