November 2017 - last edited January 2018
When you're asked to run a repair on the game client, it means you'll need to make the SWTOR Launcher start a scan to find and repair or re-download damaged or missing files.
If your Launcher is set to Streaming aka. BitRaider (indicated by the letters ST on the lower left of the Launcher):
If your Launcher is set to Non-streaming (SSN):
Note: If using streaming (bitraider) launcher the repair function on the launcher used for non-streaming is disabled and will never enable to be run.