Reset 5v arduino from 3v source

UKHeliBob:
My question: Why do you need to reset the Arduino ?

To upload new sketches to the arduino (wirelessly).

Grumpy_Mike:
Yes

What measures would you recommend?

[Edit] Some one told me to just throw a resistor in there. Okay but it's still 5 volts, right? Would this be 'good enough'. Or should I use a transistor? I'm looking for the correct way to do it.