Individually, we do grow, I would agree. Doctrines do develop, but it is, as you say, 'deeper' rather than new knowledge; deeper understanding of the same belief, of the same teaching; change without change (I like the way you ut it).
A true Church can only 'discover' more of what it already knows.
The process of deepening our faith will continue, no doubt, in the life to come, indefinitely, for God is infinite and eternal.
Self ping