[zelos]

This suggests ejecting a secondary mirror in front of the craft to reflect light to brake the original craft: https://arxiv.org/pdf/1604.01356:

"...or by ejecting a reflector that is then used as a braking system (similar to thrust reversal on jets) but this only works if the payload is still within illumination range of the primary laser system"

[dotnet00]

Flipping the sail around would probably be the lightest option, though tricky because the larger sail designs would not be rigid.