Neuro-regeneration is a long and slow process if it happens at all. The brain does not have much regenerative capacity at that age. At 70 years old, the focus should be managing his symptoms and trying to prevent further injury.

The android apps are likely premature if he is still in acute care. Lumosity is just exercise, not a recognized rehab protocol. Brain training has been shown to benefit the tasks practiced but not improve other areas. Pushing too much cognitive effort may be counter-productive. A speech therapist may have some ideas that specifically fit his needs. Focusing on a small screen may not be good.