Much of the advice already here is good to help you step up from a sub-1000 LOC program to working on bigger applications; but if you've not been doing any coding since university, then you may find some of it a bit daunting. This is also true if your existing coding experience is in something like C or Java and you wish to work in something a bit more "trendy" like Python, Clojure or Ruby.
I find that writing programs for Project Euler problems (http://projecteuler.net/) is very handy for sharpening the saw, or getting familiar with a new language. Obviously, it won't help you get up to speed with a graphics library or web framework, or anything like that, but it will help get your mind back in good shape to follow everyone else's advice here.
I find that writing programs for Project Euler problems (http://projecteuler.net/) is very handy for sharpening the saw, or getting familiar with a new language. Obviously, it won't help you get up to speed with a graphics library or web framework, or anything like that, but it will help get your mind back in good shape to follow everyone else's advice here.