Rerunning the base path

The runner in question hasn't lost his opportunity to return to third and retouch simply because he already touched the plate. There are two instances however that would prevent him from legally returning.
1) If a following runner scored before the one who missed third returned to retouch he could not legally return and would be subject to an out on appeal.
2) If the ball became dead (e.g. was thrown out of play) after the the player who missed third was on or beyond the plate he could not legally return and would be subject to an appeal out.

pilsner's #2 answer is correct in FED, but not in OBR/NCAA.

In all rule codes, if the ball is thrown out of play when the runner is between third and home, if the runner then touches or passes home, he cannot return to a previous base to correct any missed base, and may be called out on appeal. Actually this applies at any base--when the ball is thrown out of play, the runner who then touches the next base cannot go back to a previous base.

The difference between FED and OBR occurs when the ball is thrown out of play after the runner has touched or passed home. In FED, he cannot go back, but in OBR/NCAA he may go back to correct his error. In FED the determining factor is the position of the runner with respect to the misssed base--if he is on or beyond the next base when or after the ball is thrown dead, he can't return.

In OBR the determining factor is the postion of the runner when the ball is thrown dead--if he continues on to the following base, he can't return.

As a side note:
At the high school level, including varsity, I - for one - almost never see appeals being made (on missed bases/early leave). And I see base runners missing bases all the time. In my ball playing days, the coach assigned people on the bench to watch the runners. "Dave, you take the lead runner, Tom you got following". And we used it often. Of course it created consternation since the ump didn't always see it as well. Then the coach would say to us "are you sure". Anyway, even in the very obvious misses, like rounding 3rd on a one hopper to the outfield, I'm always amazed that it nearly always is not appealed. And if there is a trailing runner who misses second ... well, forget that. It has never been appealed that I can remember. Defensive coaches want outs. Why not return to those 'glory days' and assign people to watch?

Better yet--why isn't the coach watching?