Hi,
I suppose that you're talking about the "continue shopping" button available in the checkout page.
That button is just a link with the URL you have configured in your HikaShop configuration.
Now, thanks to a view override, you can change how the button is acting and use a include JS code to perform a history back instead.
But that's not something we would recommend since you don't really know from where the customer is coming from and it might not send him to a product listing or product page.
Regards,
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.