This one? It doesn't give me any prompt...
Hmm, how about try restarting the level from the school and go back to sewer and run all the way from the sewer to the starting entrance? I have similar issue with that, I think if you keep reloading the game inside the level, the game think that you are on previous level sewer instead of "finished the school level" That's what I did previously.
Just dodged every monster cause they aren't worth for the fight