Sometimes you know there is an update for your plugin but WordPress doesn’t know about it yet. You can force WordPress to check for plugin updates by deleting the content out of the _site_transient_update_plugins row in the wp_options table.
After running the query below on your WordPress database, login into your WordPress admin panel, navigate over to the plugins page and you should see all available updates.
update wp_options set option_value='' where option_name='_site_transient_update_plugins';
Multisite version:
update wp_sitemeta set meta_value='' where meta_key='_site_transient_update_plugins';