Some ideas to test separately.

\) Can you try switching them to "Pen Japan" 1.1 months before the usual cancellation point? This could be done with an opt-in.

\) Incrementally iterating on Mithaldu's idea, can you try giving them a price break (and announcing it with an email!) 1.1 months before the usual cancellation point?

\) Can you add a "But wait! If you stay around, you can get a 10% discount on your subscription cost" last-minute notice to your cancellation page, that is only presented if the user has been around for (the mean cancellation time - 1.1months)?