Analogue-sequencer

I expect that soon after I pose this question, Paul Nagle will post the
obvious answer to it, making me feel silly. So much the better.

Suppose I have a pattern that practically of indeterminate length - lots of
probabilities afoot, affecting the pattern length and direction - things
scoots around for awhile before finally reaching step 16, where it is set
again to a length of 1.

How would I, if I can  - tell the P3 that when I reach the end of this
pattern (by playing the final step in the pattern length as set in the
pattern) to increment the playlist on another track - in other words, say
that NOW I want to switch to the second pattern on my playlist on this other
track.

Does that question make any sense?

Thanks,
Gene