The whole point of an interchangeable lens camera, is you get to change the lenses. Different lenses are designed for specific tasks, and therefore it is a good idea to build up a lens collection (if you're more serious about the hobby) so you can cover yourself for any situation.
So.... You say you want more 'zoom'. Therefore buy a telephoto. Don't buy something that crosses over the range of the kit lens, that's not very beneficial.
I would suggest...
a sigma
70-300 APO if you're on a budget.
Or a canon
70-200 F4L if you're not.
Both lenses will totally change your outlook on photography and allow you to 'zoom' in to shots you wouldn't have been able to take previously. The canon 70-200 is a great piece of kit and will last you through many cameras, It's from their professional level line.
It's worth looking for those lenses second hand too (you should be able to pick up the canon for £350 or so).