Updating a miner in ethOS is easy.
sudo update-miner claymore
The above example will update claymore to the latest version on the ethOS Update server.
You can take a look at the miners and current versions here:
http://update.ethosdistro.com/miners/versions
In ethOS 1.2.6 a command will be added to update ALL miners at once. once this is released I will update this post to give the updated instructions.