Basically this image was put here as an explanation as to why frisk doesn't just up and reset the game or reload another save file~

Sans is a sneaky son of a gun~

I was wonderin’ when someone was gona ask~

Kay see this scar right here…she hides it all the time but this scar…is why she can’t ever leave or reset.
You can only see it when in the dark, but you see that code in there…it’s a special code I made up. I learned a little from the king and that flower…during our final battle and from studying the ‘code’ of our world…I created a virus and inserted it into my attacks…one knick and it was over. If she resets, she’ll forever be destroyed…the world along with herself will be broken and can’t be fixed EVER. AGAIN.

Yeah it’s a risky bet…but I knew she would choose the right choice. She can’t reload any saves either because then the virus will corrupt that save too and glitches will come out of left field and destroy her. She’ll lose her memory, feel immeasurable pain that can’t be fixed~ so she had the choice…die forever…or suffer in pain forever~

Needless to say…kehehehe…she chose the right answer~

and that is his answer~