Hello! I liked your game! It is fun, although spamming click with swords makes it kinda easy, just click like crazy and kite back and you're set for the win... but I could not get the green stone. I killed everything (scored 91/45), got all the other stones I have found, but the green one was just not registering the collision with the player and was never picked up... don't know if the game has an ending due to this bug. Life potions were ok, but the other potion was like... what does it do? There were no UI cue of the effects!
Now, about your question on "How to update". You can do it by creating a new build, zip the folder and just replace the file in the upload section!
Itch also offers a command line utility for sending only the changes but , in my opinion, that's overkill for a gamejam.
Great job!