Many immature leeches feed on aquatic worms and larvae, but if you have it at a stage where it has already fed on blood these may not be enough. Have you considered seeing if it might be able to feed on the bacterial medium called 'blood agar' which does contain blood (and this might help remove some of the issues with blood)?
I am not sure I understand. Export to where? Why do they not have any blood? Have your tried to feed them small aquatic invertebrates to see if they eat them? Also, most blood feeding leeches can survive fairly long periods of time between their blood meals and this would allow shipping without any food in container.
I understanding what do you say. You can feed them with algae but it`s not enough. If you intend to export them, You must cut off feeding from 32 weeks ago.