In the file administrator/components/com_hikashop/types/characteristic.php you have the line:
var names = [\'id\',\'name\',\'code\',\'image\',\'price\',\'quantity\',\'description\',\'weight\',\'url\'];
you will need to add your new fields so that they are handled as well. So, for example if you have the id hikashop_product_dimension_main you would change that line into:
var names = [\'id\',\'name\',\'code\',\'image\',\'price\',\'quantity\',\'description\',\'weight\',\'url\',\'dimension\'];
Note that the modifications in that file will be overwritten when you update hikashop.