The higher your wattage the more juice you will vaporize. So turning down your wattage will conserve juice.
You could also try the 1.2Ω coil which has a suggested range of 10-30 watts. However, it may be a mouth-2-lung coil. I have not tried this coil.
Or you could get a different subΩ tank whose coils operate better at a lower wattage than the Crown coils do.