GROWING YOUR SPIRIT MAN IS DELIBERATE THING AND IT IS YOUR RESPONSIBILITY

Source

After newbirth or a person is born again he or she is expected to take on the responsibility to grow his or her spirit man.
If a mother gives birth to a child and discovers that after three years the child is not different from how he was immediately after birth the mother of a surety wouldn't be happy. So it is with God, after our newbirth God provided and kept everything in place to ensure that we grow but he seeing us after some years that we are not different from the way we are immediately after we gave our life to christ he too would not be happy.
The measure of faith that was given at your newbirth should not remain with you after three years neither should your understanding of spiritual things be same you are expected to work on it.
Your growth is based on others neither is it measured based on other person's growth, it is a person thing that is based on God's word.
We dont wish to grow but rather we grow spiritually by engaging on some spiritual exercise which include:

Studying and memorizing God's word: The apostle peter in his letter to the church he ministered to he admonished them to desire the word of God so the can grow by it (1peter 2:2) and also apostle paul in Act admonished and commended God's word to them so they may also grow (Acts 20:32)
Meditating on God's word: There is one thing to know that you have food in the dinning table and ther is also another thing to eat that food. Meditation is just like eating the word after you hqve known it. God admonished Joshua to meditate on his word (Joshua 1:8) because he knew in it he would grow spiritual and become successful physically.
Prayers: Jesus told his desciples to pray and not faint (Luke 18:1) because it is one of the spiritual exercises a believer would engage in and it would help groom his or her spirit.