Answered by Mukesh
Whether a card can be topped up is set by the brand, and many digital gift cards are issued for a fixed value rather than designed to be reloaded. In those cases you would buy a new card rather than add to an old one, which is perfectly normal.
Some brands do run their own reloadable schemes, usually through their own app or account, separate from a one off gift card. If that is what you want, the brand's own service is the place to look, since reloading happens on their side rather than through a gift purchase.
If you simply want to give more value, buying an additional card is the straightforward route and works with any brand we offer. Should you be unsure what a particular brand supports, the terms shown with the card and the brand's help pages will confirm whether topping up is even an option.