Does anyone have any experience with this mixer?

I've had it for awhile and it's great, but I have a problem that the manual hasn't been able to address (atleast not that I can find).

I want to set a riff to loop, but the only option i have is "repeat", which is as far as I can tell isn't the same thing.

Is it possible to be able to set a riff or any sound for that matter to loop at my discretion?