Select from the following update options, depending on whether or not you are using Composer.
If you are already using BLT with Composer, you can update to the latest version of BLT using Composer.
Run the following command:
composer update acquia/blt --with-all-dependencies
This will cause Composer to update all of your dependencies (in accordance with your version constraints) and permit the latest version of BLT to be installed.
Examine the release information to determine if there are special update instructions for the new version.
Review and commit changes to your project files.
Occasionally, you may need to refresh your local environment by running the following command:
blt setup
This will drop your local database and re-install Drupal.