Here's the part number:
75765-S10-910 Emblem, Rear (R)
List price is US $7.42, online price is $5.19. If you add in shipping it's probably cheaper to just get one through your local Honda dealer.
It looks like there are four pieces to the badge. The three letters, C R and V, plus the hypen symbol that goes between the R and V (CR-V). If the existing letters are still bright and shiny, then just getting the R should be good.
I believe it's attached with double sided tape, so make sure to clean the tailgate surface with rubbing alcohol before applying it.