The formation can be re-traced anywhere from 50% to 100% without violating it. Normally, a 50% re-trace is seen with a 50% extension of the drop for the target. A 100% extension is also possible, but I have not seen it too often.
For example, 1392-1330 is 62-points. 50% re-trace is COMP 1361. 50% target drop is 1299.