It happens, at least for me, all by itself.
Whenever i see things i've done a (short) while ago, i can't help but think " what a load of c*@&".
I'm not sure that is because i do grow, or because i can't master anything yet fail to acknowledge that at the time, when 'in the groove'.
I expect the latter.
This is where workshops are useful, getting critical feedback about your work.
Also just meeting up with like minded people who's work you respect and showing work, discussing ideas etc.