This series of Sony ultraportable notebook/laptop things has soldered ram, meaning it is directly built into a board and basically non-upgradable unfortunately. Based on research of this devices, however, I doubt that replacing the ram is enough to speed this device up any reasonable amount.
With that said, if you were able to:
# Discover the exact types of ram chips compatible with this device
# find these chips
# unsolder the old ram
# resolder the new ram on
# not damage any surrounding components in the process
you may be able to squeeze a tiny amount more of performance out of this device. however, it has likely passed the cost of purchasing a used device of a different kind for better performance.