Hello,
HikaSerial generates a serial but with the "coupon generator", it also create a HikaShop coupon.
What you want to update are the HikaShop coupons, not the serials.
If your "coupon template" is made for a 100% discount on a specific product, then updating the product price won't affect the previously created coupons.
Otherwise if you use a more "generic" template and use the "coupon generator" feature to match the bought product price with the coupon value ; then you will have to update the coupons.
But you might use a HikaShop mass-action to update massively coupons.
For more details the best is to open a new thread in the HikaShop section of the forum.
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.