Thank you for your question. Please follow my instructions below,
First, you need to go https://themeforest.net/downloads
Download the theme.
– Go to Your online store
– Upload the updated version of your store.
– Click “Edit code” of the current version – http://prntscr.com/lcyjmo then open “settings_data.json” and copy the code.
– Now click “Edit code” of update version then open “settings_data.json” and paste code – http://prntscr.com/lcyjfb
I’ve added details with video in the docs.
Docs link: – https://demo.hasthemes.com/doc/lezada-shopify-theme-v2/index.html#updatetheme
video link: https://drive.google.com/file/d/1xUqFTBRBsgJTGFFxsQ3jJEXkTeI1CDHf/view?usp=sharing
NOTE: If you have added extra code in your existing theme. You will lose additional codes. So, you need the backup existing file. And again you need to add additional code to your updated version.