The 550D is a good camera, no reason to change it for the next 2 years at least, unless u wanna go full frame. I think you should get new lenses if your kit lens is not enough for you. For us to recommend one for you, you should tell us what you like to shoot.
We can't read minds you know... without knowing WHY you feel that your current lens (I assume kit lens) is limiting you, how to know what lens to recommend?
We also dunno what your budget is.... and so on.
It isn't so much about what we think, but what you think?
What is your current lens setup? 18-55mm that comes with the camera? Do you like the range? Do you have problems taking in low light conditions? Do you want something to cover a longer range? And what kind of photography are you into?
There is no right or wrong lens as it depends on the individual.
Your bros on clubsnap are always ready to help, but you need to help us help you
actually keep your camera, choose one or few lens according to your shooting preference instead.
Lens can keep longer then camera body.
But if you intend to upgrade to FF someday, it will be wiser for you to start investing in EF lenses not EFS lens cos by then it may not worth alot and harder to sell (seeing more and more ppl going into FF these days).