You can help keep your knives in tip-top shape if you hone them regularly using a honing steel. Honing does not replace actually sharpening them though, the mechanics behind honing is it straightens out the blade that may be bent on a nearly microscopic level. It will not shave off metal (unless you have one of those new diamond honing rods, I wouldn't recommend buying one of those), and give you a new edge.
When you hone your knives you usually don't need more than 5 passes on each side to effectively bend the edge back into place. If it takes more than that for you to notice a change in cutting, then you need to sharpen it. I will have a post on sharpening your knives soon.
Also please be careful when using knives. Before I actually learned all these things, my knives were REALLY dull, and I was never worried about touching the edge. After I learned to sharpen and hone my knives, I was in the bad habit of not being careful, and cut my fingers many times.