Updating

You should update package via composer

$ composer update

After update you should run artisan command for update assets:

$ php artisan sleepingowl:update

or

$ php artisan vendor:publish --tag=assets --force

And clear view-cache

$ php artisan view:clear

You can add this command to composer.json for auto updating assets

{
    "scripts": {
        "post-update-cmd": [
            ...
            "php artisan vendor:publish --tag=assets --force"
        ]
    },
}