You can spot apply with weed killer. In this case, I'd suggest Round Up as it doesn't ground travel well, just make sure it doesn't touch the juniper at all. A lot of us do that by wearing latex or Neoprene gloves (even two pair!) and painting the leaves of the dandelions with the RU.

Removal with something like a Weed Hound also works. Some will come back from their tap roots, but not all, and not if you keep after them. Tap roots don't last if you keep breaking them off. :-)