Spiritual refreshment, benediction and blessing are all symbols connected to dew.
Psychological / Emotional Perspective:
We may need to accept that gentle, and not forceful or overpowering, emotion can cleanse us of whatever is troubling us.
Everyday Material Aspects:
Dew or gentle rain falling in a dream can represent a sense of newness and refreshment we have perhaps not been able to obtain, except from an external source.