OK. I am going against the grain here but would better lenses improve the IQ of your shots ? Yes. Of course they will. They will improve sharpness, clarity and contrast, they can give you lower DoF - if that is appealing to you and of course to many it is because that is what gives photos of certain subjects much of their oomph, and of course certain lenses are liberally sprinkled with pixie dust to produce magic
What they can not do is improve your technique, composition or 'eye' for a shot, but shot for shot they will give you a better image. The Pentax kit lenses are good but if someone were to seriously suggest that a lens costing ca.$100 new can produce the same IQ as a lens costing many times that ......well enough said.
Just be aware that there is no direct correlation between price and image quality. For some lenses you will be paying more for the build quality, WR, SDM, HSM, name, focal length or other features. A $500 lens won't give you 5 times better images than your 18-55 but they will be noticeably better in the right hands.
I would go along with the advice given to get the most out of what you have now until you feel you are ready for the next step and then decide, based on what you feel is lacking and on your preferred focal lengths and maybe on advice given on this forum, on your next lens.