Assuming the craft could carry a few small thrusters (and assuming technology has improved enough to make them small enough without affecting the overall mission), they could be fired to turn the sail and spacecraft and stabilize it with Proxima shining at its back, effectively slowing it down for at least a longer…

After searching endlessly, Time was his.

Bored, she played with the universe...

Drifting hopelessly in the black, lost.

We will NOT abort this mission!