I killed Mettaton NEO and then proceeded to go all the way to Sans and talk to him. I stopped there. I'm trying to finish the Genocide route, and I believe my problem is at Mettaton, where I killed him too early. It says I have "34 left" but lets me proceed to the "New Home" anyways. Is there a way to go back, or do I have to start completely over?
(Note: I also know how to change the game's files, but I have no idea what all the row's values mean. A link to a guide would be GREAT.)