That constant rain should definitely wash the neem away, reapply neem every 7-10 days until they start glowerimg then i would stop the neem (the buds will start soaking up the neem and burn your hairs, might get bud rot if the flower doesnt dry out fast enough). Also apply neem in late afternoon or evening so the sun doesnt cook the oil into your leaves and damage/burn them. As for that 10 day straight rain, try and get them out of the direct rain like under a big tree or against a house or shed so that the roots aren't getting soaked to death. You should be okay during the veg stage with the rain but once they start getting big flowers, rain is your enemy so try and keep them dry at that stage.