If PRMagmaPersistency is enabled, then each change to a PRKernel should
be saved in the database, a restart without saving the image) should
pick up the changes.
The application that has Pier and Magma, should have a "Magma" control
panel, and a "Pier"
control panel. You can use the "Magma" control panel to see the open
magma sessions and each
of these should have an "explore" link which opens an explorer.
However, the "Pier" control panel, "Persisted Kernels" section also
has
an "(explore)" link which opens an explorer
so you can see exactly what is in the database.
If you find that your kernel is not actually being persisted, then you
may have an older version of Seaside28Jetsam. I would make sure that
that is up to date.
Keith