It all depends...you might try 4k7 as it could still work. If it doesn't, try 3k3 as it gives roughly the same current/pullup strength at 3.3V as 4k7 does at 5V. If that still doesn't work, you need to rethink your cabling layout as OneWire should easily work over a distance of 15 meters with simple pullups. At such distances, active pullups / line drivers aren't really necessary.