You need to take a vampire prisoner, and milk them, like the damned leech it is.Milk them dry if you need to; higher blood potence means it will take more of their damned flesh to satisfy you, not merely sustain.

(Blood farming the vamps won't restore thirst, you have to hunt, or actively choose to drain them for thirst reduction to take effect. Blood-tithe of the kin variety from a domesticated livestock kinda works, but still wonky from my obs)

Or, go full on Hannibal the friendly cannibal. Ensnare the spider in your web for dinner, hunt and drain your prey from the comforts of your prison cells in a way that would make the Tremere shudder, and the Tzimisce blush a rainbow.

Apex predator is a lie the leeches tell themselves in the name of their own superiority. Help them celebrate their lack of immortality by bathing in their stolen tithes of blood they sought to drown mortal kine in, and celebrate their eternal damnation coming early for them.