Not enough info for an accurate answer.

We know you have the mixer, and the computer that you are recording into, and monitoring from. We know you are monitoring the computer 'audio out' through the mixer. We don't know how you are recording INTO the computer, or if you are going into and out of the cheezy computer soundcard, or through an audio interface. We don't know what software you use to record your audio.

I'm guessing that you want to play or sing through the Xenyx, into the input of a computer soundcard, and then want to monitor the recorded tracks from the computer soundcard out, and then through the Xenyx, while recording another track?

Tell us more to possibly get an accurate answer. please?

Kapt.Krunch

your headphone output on your interface goes through channel 1.
use the effect bused through your mixer. Out put of your mixer goes to your performer. through via headphone jack

this will leave all the instrumentation on top of the VOX with whatever reverb effect you place on it. but it should deliver what you want. While still giving yourself a dry VOX performance to edit to your choosing.