Why is it necessary to reschedule a modified concurrent program

Hello,

Context:

One concurrent program.

One daily scheduled request calling this concurrent program.

Modification of this concurrent program.

Question:

Why is it necessary to cancel the scheduled request and reschedule it so as to be sure the corrected concurrent program will be executed?

Is there information of the previous concurrent program saved somewhere for the scheduled request?

If yes, could you detail this procedure?

Thanks in advance,

Armel