If you’re in China already, there isn’t much you can do if your VPN’s site is suddenly blocked. As such, it’s better to be proactive: before you arrive in China, we recommend making a note of alternative URLs, support email addresses, and manual connection processes for your device.
Think about how you’ll store this information. If your VPN goes down unexpectedly, you won’t be able to access cloud storage services or messaging sites. Ideally, relevant information would be kept in a locally-stored, encrypted file on a password-protected device.