Gary, unfortunately there is no way to bump an old article directly. The article listings are strictly chronological unless you are using the search function.
Now, there are some ways to get an older article more attention. For one, posting a new article and noting some of your old work can draw people to some of your older works. When they visit your blog page they can look at all of your past articles in chronological order. I do this often when members post, an I like their work.
Another way to re-feature work can be to create a series link (perhaps not the best name for it). When posting articles on a pc, I believe you still have the option to link like articles. This may not help you in every instance, but you may be able to highlight an older post this way.
All this aside, the rotating features at the bottoms of the pages are likely to show your work for people from time to time.
