Yes, 2.5.1 will have on click update.
You will need to setup via Appearance -> Theme updates
Use the following steps to update your Evolve Plus Theme, NOT child theme.
Your child theme should contain only style.css and functions.php and no other files…
We do not encourage using of Child Theme, it does not work properly with Evolve Plus Theme.
1) Unzip downloaded update on computer.
2) Use FTP to download a copy of the existing Evolve plus theme from your server for a backup on your computer.
3) Delete the Evolve Plus Theme on your server.
4) Upload the newly unzipped copy of Evolve plus from your PC to your server.
Some time overwrite will not work properly, leaving some old files and causing weird actions..