Yes third party software like Neros InCD will do just that. However when I tried it, and this was a few years ago there were problems, so much so that I stopped using it. I'm sure there are other programs as well but I never use CDRWs any more as they are just too unstable. Far better in my opinion to use a standard CDR and create a multisession disk and just keep adding on stuff till its full. My CDRW disks went in the bin years ago when I couldn't get some of the information off them.
Its Nero I use, when you get to the final screen on it where it says BURN theres a box you can tick to create a multisession disk. Just tick that and you can keep adding till its full. I use Nero 6 and I assume that its that version you have.