Only options I see at the moment:
If that coalition that Marley put together is on the way. This only works if they’re in transit; and can target Eren and the Titans while they are on the island.
The cerebrospinal fluid of Ackermans are resistant to brainwashing. They could feasibly extract enough for a vial. What they do with it is anyone’s guess. Maybe find some way to inject it into Eren’s spine to jam his signal. The rest of the titans would be able to shift in that timeframe.
Gabi’s talk-no-jutsu works. Eren feels great remorse for his actions despite planning them for years. This is of course, stupid.