Instruction - what to do when your rider crashes, a lot! by Colleen Millsaps
The cliché, "if you're not crashing you're not trying" has a lot of truth to it. Crashing is definitely a part of learning to go faster and pushing the edge of what each rider is comfortable with.
Riders always seem to go through periods where they crash a lot and then they stop crashing, and they're at another level.
Unfortunately there is no convenient time to crash, other than practice, but try to be patient and remember the big picture, that this is all part of getting faster on a dirt bike.
When you talk to your rider after a race I would focus more on how he or she was riding before a crash. Point out the things he or she was doing well.
Most importantly, if we as parents keep making a huge deal about crashing, it will continue to be. Try to be patient. Tell your rider that crashing is OK because it means they're about to hit another level of speed and that is a great thing.
Good luck !