This a quick exploit I found that allows you to run the same heroic as many times as you like. Here is how you do it...
1) Make a group via LFG Specific or Random. Have atleast 1 other from your server so you can join LFG again later.
2) Clear the instance until at least saved. Full clears are obviously the best.
3) Everyone but the leader leaves the party.
4) Leader kills himself inside the instance.
5) Leader re-enters the instance to find it completely reset.
6) Reform the party and/or join LFG again.
7) Repeat
I found this by exploring PoS after the group had left. I died from a jump then when I re-entered the instance all the bosses had returned. Seems to work for all instances that you can kill yourself in after a clear (All of them?)