It might also make sense for students to occasionally transfer in. If the school has a low reputation, maybe you're accepting students who were expelled from other schools. If the school has a high reputation, maybe rich parents are transferring their children in because they aren't happy with their current school.I doubt it would have a very significant effect on the total, but at least it wouldn't be entirely static throughout a year.
I kinda wish your rules did more. For most of the game, you're chasing events to get the changes you require.As compared to Students and Surveillance, the Cafeteria's income is awful, especially given its cost. Anecdotes aren't exactly data, but: 312 students. 70 rep. Student money: 108.69 (Rate per student; 0.3483) Surveillence Money at Level 2: 39.81(Rate per student; 0.2251). Cafeteria money at Level 3: 9.98(Rate per student: 0.032).