Hi,
If you didn't modified the core files, you just have to backup the database (all "#_hikashop_" tables), the "media/com_hikashop" folder and the "templates/YOUR_TEMPLATE/html/com_hikashop" one (for the view overrides).
For HikaSerial, it is the same kind but the "media/com_hikaserial" is not required except if you put some images into (for the plugin "attachserial").
All HikaSerial content is stored in "#_hikaserial_" tables.
Regards,
PS : The Joomla plugin table could be useful for parameters of some HikaShop plugins.
Jerome - Obsidev.com
HikaMarket & HikaSerial developer / HikaShop core dev team.
Also helping the HikaShop support team when having some time or couldn't sleep.
By the way, do not send me private message, use the "contact us" form instead.