The auction is dead and gone and you lose any selling offers. You have to relist at the standard rate (unless you wait until the next selling fees offer comes along[1]).
When you cancel you'll probably see an option to immediately relist. This will be at the standard rate.
You can perhaps make second chance offers (if it was an auction, not a BIN) but note that if accepted these will be charged at the standard selling fees rate, not the offer rate.
Yes, it's very annoying.
Footnote:-
1: If you listed an item under a special selling fees offer and it didn't sell or the buyer did not pay, you could wait and relist it when the next selling fees offer comes around. At the moment, reduced selling fees offers seem to reoccur every two weeks. But be careful, do NOT use the 'relist' option. This will, if I understand correctly, charge you at the normal fees rate! Instead create a brand new listing using the 'sell similar' option. This creates a new listing and you get the reduced selling fees offer rate on that listing.