This is a very good question. Refills are a new habit for many people, and it's different than just using a product until it's empty and throwing it in the trash.
YES, it is a great idea to clean your JELLY and TONIK bottles before refilling them, especially JELLY, which you may note can leave some stubborn traces in the bottle. At our houses, we put them all in the dishwasher for a cycle—sometimes that's the only way to return a JELLY bottle to its pristine "new" state.
When a refill is done, the droppers and spray tops should also be cleaned. For the dropper, the glass part comes apart from the rubber dropper part so that you can also sterilize that piece. We also offer free replacement spray tops on the website so people can get a new one anytime on their refill journey.
Sanitation options include dishwashers and isopropyl alcohol. Many stylists also use a salt-water solution in their salons without dishwashers, which Jared says works as well.
Feel free to let us know if you have any additional questions.