Propagate topological changes from base shapes to their target shapes

To update my blend shape deformations

Make a topological change to your base shape’s geometry.
Select your blend shape deformation’s base shape.
Select Edit Deformers > Blend Shape > Bake Topology To Targets.
The topology of your target shapes change to reflect the topology of their base shape and all your base shape’s modeling history is baked. See Edit Deformers > Blend Shape > Bake Topology To Targets.