Congratulations on a very successful platform! (Success should be measured in usage/reach, not $).
You've probably thought of this, but it might be easier to charge a very small amount -- say $1/month, which most people even students, could afford, rather than rely on donations. If you get 1% of users paying that, it's still $20K month which is more than you're getting now. (Of course managing the payments themselves costs money).
It can still be non-profit (which is a great thing), so no one is getting rich off of it, and it doesn't poison the mission. But it could pay the bills.
Update: Processing fees are a problem as posters have pointed out, so you'd probably want to make it $10/year, or $5/six months. It's still an easily decision for a very large number of people.
Patreon has $1/month options, not sure how they do it though.
You've probably thought of this, but it might be easier to charge a very small amount -- say $1/month, which most people even students, could afford, rather than rely on donations. If you get 1% of users paying that, it's still $20K month which is more than you're getting now. (Of course managing the payments themselves costs money).
It can still be non-profit (which is a great thing), so no one is getting rich off of it, and it doesn't poison the mission. But it could pay the bills.
Update: Processing fees are a problem as posters have pointed out, so you'd probably want to make it $10/year, or $5/six months. It's still an easily decision for a very large number of people.
Patreon has $1/month options, not sure how they do it though.