if there was a time in his life when he did feel "more spiritual" i would ask about that time, what he thought it was about that period in his life that helped him feel that connection and see what your family can do to reintroduce that element into your life now, whether by adding a specific practice, clearing things out of your schedule, changing something about the home environment, whatever.
if there are no periods in his life that he can look back on like that - if he's wanting to experience something for the first time - then i suppose that's trickier. ask him about his ideal circumstances for spiritual development. he might say a communal work farm, he might say isolation, he may say monastic life, but whatever it is, there can be small changes like volunteering, more time in nature, more time alone, etc that could move him a tiny step toward that ideal.
some people gain a lot of benefit to things like, a weekend retreat, or energy work, or whatever, and others feel like, "that was great, but now that i'm back to normal life, that's over." and the benefit doesn't carry over. but it doesn't hurt to try . . .
i think it's true that he'll have to be the one doing things for himself, but that doesn't mean you can't help him figure out what to do and support him in it.
