Once you get a student (aka, a customer) in your system, always market to them additional opportunities to expand their knowledge and them spending money with you. AKA, create brand loyalty.
US Aviation at Denton, TX is where I got my PPL. Great facility, aircraft, instructor. But absolutely no interest in keeping me spending my aviation dollars with them. They are very wrapped up with their contracts to train overseas pilots (mainly from China) in their Part 141 professional pilot program and exhibit no interest in training local domestic students as Part 61. They are right here on my home field and it would be great to use them for CP and CFI. And we have a large local pilot population who would also seek out a "within 15 mile" solution for advanced training. But he doesn't want us. And he doesn't want Part 61 folks like me to return and spend money with him.
So a successful school owner needs to market to his existing customer base and encourage them to return. Hosting the free WINGS seminars, sending out mailers, offering deals on block rental rates, etc. The existing student already knows and appreciates your brand. So you should do what's necessary to keep him informed of what more you offer and the high value of staying with you versus a competitor.