Whether you have a new upsherin boy, or simply an active boy of any age, one of these two products will work for you.
These two items are always well-stocked in my house. Even though I don’t have little boys anymore, I do have active boys who don’t want to worry about their kippah falling off when they’re playing sports. Each of these products is preferred by different male members of the family. Depending on your son’s hair type, one of them might help your upsherin boy keep his kippah on, from age three and beyond!
This is a recent favorite, and every time we visit a Judaica store for a sefer or book, one of my boys is most likely adding a new kippah and a pack of these Keep-Kippah clips to the checkout counter. They’re sort of like a wig clip, but you stick them inside the kippah (they have an adhesive back) and they’re not visible (unlike other clips often used on young boys, which are). You can get them on Amazon here (sold by a Jewish vendor) or from Judaica Plaza here or Eichlers here.
The next option has been around forever: simply velcro. You can buy velcro strips in the Judaica store as well, but if you want to have a lifetime supply available anytime there’s a new kippah around, get a roll of velcro! You only need the “hook” side (although we haven’t found a roll of hook tape on its own for cheaper). Simply cut off a couple of pieces and stick it in. The “hooks” somehow attach to the hair and hold it in place. I don’t think this will work well with long hair.