Set ping-pong mode

Multi-select all slices (e.g. hold one slice until it fast-blinks, then hold write and let go of the slice you were holding, now - still holding write - select all 16 slices until they all fast-blink).

Still holding write, press the value knob repeatedly to select the "ModE" parameter. Turn the value knob to set it to "PinG". This mode ("ping pong" mode) plays a slice to the end, and then starts playing the slice in reverse until it is back to the start of the slice. It then starts playing forward again, and so on, and so forth.

Combined with each slice playing until the end of the master sample, and playing backwards and forwards continuously, means that you will never run out of audio for the duration of the note/step you program. It will furthermore play fragments of the master sample in reverse, which can add to the sonic complexity of your new break.

Of course, if you wish to deliberately run out of audio, you can use a different slicing mode and/or turn off "ping pong" mode.