If you add refrigerent you'll need to at least know low side pressure so you don't overfill. It's best to have a set of hi/lo gauges before you add refrigerent because the problem may be the compresssor clutch or condensor fan and not low refrigerent. First I'd lift the hood and see if the clutch is engaging and the fan is operating as there may be enough pressure to activate them but not enough to give cold air. Also check the compressor belt tension. I think some of the refill cans have an attached pressure gauge which I'd recommend, but the correct pressure is related to ambient temperature. There should be a chart on the package of the refill kit, but you're probably looking for about 35psi at about 90F. Put the system on recirculation with the doors open so that hot engine air is not sucked into the vent system and engine RPM at about 2000, slowly fill a bit at a time to let the system even out. Don't hold the engine at 2k for too long as you could overheat the CAT and may trigger the check engine light. 134a, which is your refirgerent, leaks faster than the old R12 and some of the new replacements, so gettting the leak fixed is advisable.

The sealant is usually to soften and swell the soft seals like o-rings, but it will not work on the compressor seal, which on a 95 is more than likely where your leak is. If you see a build up of black greasy dirt behind the compressor clutch then that would indicate a leak at the shaft seal. If you continue to refill a leaking system then you'll need to add oil to the system, but that becomes a guessing game as to how much. One small can of refrigerent with oil can't hurt, too much oil will reduce cooling and could harm the compressor. There is also a dye in some refill kits that will help with finding the leak. If it's the shaft seal then that should be able to be replaced without buying a new compressor. Here's a good place to get A/C parts, tools, etc. http://www.acsource.com/index.asp