Apple has released a new update for their apple watches which takes the software version to v2.1. This update is 57 MB in size and brings performance improvements and several bug fixes.
There are many security updates and support for some more languages is also included in this update. Issues regarding the calendar complication, third party app launching and power reserve mode are also fixed in this update.
This update can be applied to your apple watch by launching the watch app on your iPhone and then going to general > software update.
Source: Mac Observer