Depends on what, exactly the problem is. Any bugs on the affected branches that might be sucking them dry?

I'd suggest just going ahead and giving it a nice deep slow soak. If it's drought/water stress it might help. If it's insects, it won't hurt, and if it's a disease, well, it's already in trouble so you've got two out of three benefits covered with a good soaking.

Let us know what you do, and how it works out. Good luck, I really like ceanothus. I plan on putting in a few this autumn.

Take care,
Grant

Since we don't know what the situation is a deep soak COULD hurt. If a soil moisture problem is thought to be involved dig next to the plants and have a look, instead of wondering and assuming.