Trouble connecting to HP C4780 printer

Hi all,
I've had the HP C4780 wireless printer for about a year and half now and every few months it seems to stop working on me. For the past few months it wasn't working at all, so I did some research and saw that the latest updates to the Mac OS included all of the drivers necessary to install the printer. So I uninstalled all of the HP software, as recommended, from my computer and downloaded the most updated drivers from the apple website. When I first did this, I was able to add the printer wirelessly by clicking add printer from the Print & Fax menu, just like the instructions I've seen said. It added the printer, and it was working fine. However, for the past few days, the printer has shown up as "offline" and will no longer work. I tried resetting everything and repeating my steps, but my Macbook can no longer find the printer. If I run the network diagnostics on the printer, it passes all of the steps and says it is connected to my router. Obviously, my Macbook is also connected. Any ideas as to why it's not finding the printer? Any help would be greatly appreciated. This printer has been beyond frustrating!