See above, the resistance will probably drop with temperature. You can measure it. Cool it, then take it out and quickly measure the resistance with short cables, or (better) do a 4-point measurement with the resistor in the liquid. You can even use the heating setup for this measurement: Add two cables to measure the voltage drop at the resistor, you already know the current.Will it be significant? Because when I have the resistor our in air, it get pretty warm (about 80 deg C or so) so I thought it's probably fine to ignore the dissipation from cables.
If this will be in a vacuum later then heat transfer from the environment to the dewar will be greatly reduced. You should take this into account.
Why is it so important to get rid of the liquid nitrogen or argon remotely without access to it?