I say either way. It's all about getting comfortable with your equipment. If you can shoot comfortably with what you have then you don't need to buy anything.
Lots of people only buy a new dSLR because it's there. They most often regret it saying they want their old camera back because they love using it more. If you are wanting a feature found on a newer model that you think can help you shoot much easier then by all means, get a new body. If not, you would be better off saving for a new lens instead.
As for lenses, you only buy if you find that your existing lenses are giving you difficulty on taking a specific shot. Let's say you only have the 18-55mm kit lens. It's good for almost everything but if you always want to get closer without leaving your spot, get a longer lens, longer than 55mm. If you continuously step back to get more of the scene, get a wider lens, wider than 18mm. If you are finding yourself shooting more frequently in low light conditions, get a faster lens, one that has a lower f/number than 3.5. If your interest is to make small subjects look large then get a macro lens, one that gets as close as you want to your subject.
Different lenses have different uses. You don't have to get them all. Some people actually believe in using just one lens ever!