you wont find too many passive crossovers that have 3 channels on them these days the best answer has allready been given in saying replace the resistor .
failing that your only answer is to find either a new set of passives (different makes will all run different ratings and x over settings)

i will check thru some old stock i have kicking around in the loft but im pretty sure most are only 2 way , i seem to remember having a pair of old kenwood 3 chnls but i will have to check .