You shouldn't. I think I remember the earlier gens having a problem with an o-ring on the outlet of the compressor though. Not the easiest thing to get to, but reasonably easy to replace. I guess it had a bad habit of going out and would cause leaks. That could be your problem. It should be a sealed system, so it would only need recharging if it's got a leak somewhere.
Also check the Schrader valve at the high and low pressure ports for a leak. This is easily done with the old spit test like we used on bicycle tires. If the valve leaks it will cause the spit (or soap film if you prefer) to bubble. If a leak is present, tighten the valve stem with the appropriate tool. If still leaking, the valve stem needs to be replaced...which can be dangerous to do given the pressure in the system. You may want your technician to do this for you.
Additionally, there are more "O" rings to consider. A refill with R-134a containing fluorescent dye can help you pinpoint the leak...especially if you use a strong UV light and the special glasses.
I had a bad discharge hose on my 97 GTS. That's the hose from the compressor to the condenser. It probably only leaked when there was pressure in the line so it didn't show up with leak detector dye. The hose had wire loom sheilding on it and I found the hole (more of a scuff) by accident when I was changing the compressor. There are a lot of opportunities for leaks in the system and slow ones aren't always easy to find. Good luck.
You most definitely have a leak . I would put some die in the system to verify where . I am currently replacing the seal on my compressor, the die I added worked well and confirmed the leaking seal. Good luck.
In both my '96 RT & 2000 GTS.....the worst A/C leak was where the line connects to the condenser. On the drivers side, the line comes down into the compressor. You can see it looking though the bumper. I replaced the o ring by removing the air filter box, and the panel in front.