I think that you already received some very good advice.
To sum up, if you want to change body for the sake of changing, why don't you consider a K-30, especially with all these new funky colouts coming up? The K-30 has possibly the best video capabilities among the Pentax dSLR.
You will see a drastic imporvement in IQ, you should get better glass: ie 'new' lenses especially primes.
- The DA 35 f2.4 is a great option to start: AF, great IQ, relatively chear;
- Older manual lenses are another direction is you do not mind MF; Pentax offers a bacwards compatibility and you can use 'vintage' lenses on your K-r; There are for example some excellent old MF prime lenses about $100-200 at the PF markerplace, sometimes even lens.
- If you are for Pentax in the long run, and have financial means, you should consider the limited series. Pentax offers two current series of limited lenses: i.e. the 3 FA Limited lenses (FA 31, FA43, FA77) regarded possibly as the best lenses across all brands (
http://www.luminous-landscape.com/columns/sm-02-05-02.shtml); the DA limited pancakes lenses (DA15, 21, 40, 70). These lenses are fantastic. You do not need all the series but each lense among these series are superb in their own.
Hope that the comment may help.