In Xiaopan and Beini you cannot. As it is a live CD, USB or ISO. Settings revert back when you restart. Therefore you can use a virtual machine software to suspend the VM and close it down. Then reopen it from a suspended state and the session will be restored. See here
You can copy the .wpc from usr/local/etc/reaver to a usb drive before shutdown and replace them before you start reaver on restart.
Adding to this post, just to be clear, saving the .wpc file from the usr/local/etc/reaver to a usb drive will only save the .wpc file from the 1st start session. If you plan on saving multiple progression .wpc files, those are located in the tmp/minidwep directory. Just save the .wpc file located there and when loaded into the usr/local/etc/reaver directory after start up it will continue from the last known percentage. This has worked/helped me tremendously with crashes/wifi signal loss that requires restart and hope this helps someone else...
