There are some steps you can take to improve your battery life. http://www.samsung.com/us/support/troubleshooting/TSG01003232/ Please let me know if these help.
If the steps listed in this thread are not helpful, repairs would be the only other option available at this time. You are welcome to private message us here with the full model code and serial number (IMEI number if it's carrier based) and we'd be happy to get this set up for you.
I'm having the same issue after the update, called Samsung and the tech was a jerk and told me that it can't be software because no other complaints have been logged...liar, just do a Google search once. Told me that my watch is no longer under warranty, I just bought it in October 2018. Very unhappy with the service.
I was told I need to send the watch in to have the battery changed and I would have to pay for it. My watch is only 8 months old. I've tried everything to fix the problem including a reset and nothing helps, this is frustrating and I can't even get a day out of the battery, this update was to enhance the battery, dont they test these updates thoroughly before releasing them ?
Amazing that they don't seem to test these things. Then to make it worse they deny there's a problem. Same thing happened when I updated my Gear S3 to the latest Tizen at the time (late 2017 I think). It halved the battery life. Again, they had claimed that the update would improve battery life. I love my galaxy watch how it is now so I won't update, but annoying not to be able to use the latest version of the software.
my watch: S3 Frontier
I have serious battery drain problem after One UI update. Prior to One UI update, I was getting over 24 hours easily, and immediately after the update, I only got about 6 hours. This doesn't get me through the day. It's is useless now if battery life is stuck at 6 hours. Samsung! I hope you see this message and FIX battery drain problem ASAP or you will lose another loyal customer!!!
Battery drain problem
Need to fixed it
I update on 29/05/19.
Not in use watch also battery drain fast.
Before 2.5 day running
After the update only 1 day battery is going on.
Very big problem plz fixed it.