Fippa does not recommend changing the reserve on a listing once the listing is live as it changes the nature of the value of the business for sale and will affect how people view the listing.
Raising the reserve can cause negative comments from buyers as the price has suddenly increased and also may cause you to lose watchers.
Dropping the reserve can likewise cause some questions from buyers as they wonder why the value of the business has been suddenly downgraded.
Always think carefully before changing your reserve whilst a listing is live.
If you do decide to change it, you can do so by clicking on the "Edit Listing" link on the auction listing.
However, there are some restrictions on the changes you can make.
You can't change the reserve price once it has been met by an accepted bid.
You can raise the reserve price as long as it hasn't been met yet.
You can lower the reserve price, but you can't set a new reserve price that's lower than the highest accepted bid. That bidder will already have been notified that the bid didn't meet your reserve price, so your new reserve price needs to be higher than that bid.