How can I monetize an english e-learning website?

I have an English e-learning website provide text chat, audio and live lesson via Skype. my customer are student and office worker who want to improve English speaking. Now, I earn money by learning fee for each lesson, but I want your advice about monetizing the website by other ways and the best business model.

What you can do is to record your lessons and give people access to it (something like 5 lessons videos for free, more for fee).

In that way, you can earn money several times for the same content.

Or you can do the "Skype lessons" for more people at the same time - some kind of class. Your students can be interested by the question of other students and it can be a win-win solution. And of course, you can charge all of the students (the price should be lower than for one-to-one lesson, but in sum, it should be more - so at the end, 1 hour of your work can bring you more).