Instead of blowing and blowing until all the tinder is spent, add more tinder to your smouldering tinder. This tinder does not have to be prepared, you can just add a plant tinder as is and it will char when in contact with the smoulding tinder you are already using. This will add heat, it will also last longer until the kindling has caught fire.
Uncharred Bracket Fungus added to my tinderbox.
Uncharred Punk Wood added to my tinderbox.