Population growth (at a much lower more sustainable rate) can be incentivized by literally paying people more money to have Children. And did it occur to you that perhaps our low birthrate has something to do with the increasing lack of opportunity to improve in this country?
Finally, I am actually against the concept that the country must have constant population growth. Population growth comes in natural waves where some decades it will be high, and in others it will be low. The drop in birthrates many believe will cause a "sky to fall" scenario, which simply isn't true. It is parasitic to expect and demand constant population growth, especially at the cost of people's standard of living.