Hi Yamanaka, in the wild, neps (other CPs too) grow in poor nutrient content soil, that's why they evolve to grow pitcher to "catch" insects/bugs for their nutrient supplement. If nutrient is easily obtainable from the soil, the plant would not waste so much energy to grow pitcher.
Repot the plant quickly, the minerals in the soil may harm your plant, use what SirKristoff suggested, or you may also use a mixture of burnt soil, coarse sand/perlite, charcoal (break into small pieces), sphagnum moss. Make sure the mixture is airy. My rafflesianas & amps love it.
