While it's true that Goku is somewhat absent in Gohan and Goten's lives, it's never without good reason. With the exception of when he's training on Yardrat, the only time Goku is not in his sons ...
Dragon Ball Super Chapter 102 picks up shortly after Goku and Vegeta since Gohan’s ki, and sees Goku then inviting Gohan to a new sparring match on Beerus’ planet to test out this new form.