You can update Sailing theme via 2 ways: via Thim Core and via FTP.
1. Update Via Thim Core
Thim Core plugin allows to update theme without resetting your settings and customization. However, you should always backup your files and databases before updating.
Follow these steps below to update Lux Hotel theme via Thim Core:
Step 1 – Visit LuxHotel > Dashboard > Updates.
Step 2 – Click Update now.
2. Update Via Ftp
Follow these steps below to update theme via FTP:
Step 1. Log into your Envato account on themeforest. In your Download page, find Lux Hotel theme and choose the Installable WordPress Theme.
Step 2. Login your FTP account via FTP software to access your host web server. Navigate to wp-content/themes folder to backup your current Sailing folder if needed. The contents on your site will not be lost but if you have modified the code then the changes will be lost. You have to modify them again after updating.
Step 3. Extract Luxhotel.zip that you downloaded from themeforest
Step 4. Upload new theme folder Luxhotel to wp-content/theme to override the existing files.