Yes, you can vape shortfill without adding nicotine. Some people top up their shortfills with a base mix which compiles of propylene glycol (PG) and vegetable glycerine (VG). This does not affect the flavour of the shortfill but makes sure that you have 120ml of e-liquid to vape without losing any flavour. If you don’t add base mix you will still get to vape 100ml, and the flavour may taste stronger. Some people who have quit vaping nicotine still enjoy having the habit of vaping and puffing on something, so no nicotine is the best option for them.