You can try rubbing in oil (castor / burdock). One of my friends used this method to start growing.
But we must not forget that hair growth is associated with our hormonal levels. Maybe that's the reason.
There is a remedy for hair loss called Minoxidil. Well, they say it can be used to speed up beard growth. True, it will have to be used on an ongoing basis.
You just need to shave more often. It's simple. Shave off the stubble as soon as it appears (several times in a row). A thicker one will soon grow in its place.