Assuming that there are no additional electrical loads, because you didn't mention any - I'd suggest you start having the electrical system, including the alternator, checked - the OEM alternator is more than adequate to run the normal electrical loads.
If you have added loads, the next step would be to let us know what they are, so you can be advised properly - there are ways to upgrade the alternator, and kits to do so - for general replacement parts, check RockAuto.com, genuine Suzuki parts can be sourced from Megazip.net, and offroad related parts can be found at Low Range Off Road.