chas2008 is correct, the aircon smell is nothing to do with the system needing regassing. The fact that the aircon is working correctly is the very reason that causes the smell in the first instance...hence the need to use a interior air treatment aerosol from time to time, and remember to set the air control to recirculated air or else it won't have any effect.
Also, I believe it helps to switch off the air conditioning 5-10 mins before the end of a journey, that way the condensation within the system will have a chance to evaporate before shutting the system down.