There's a linked progression to 10k if that's what you want to do. Otherwise you can try to gradually improve your pace, find new routes and vary length of your runs e.g. 5, 6,7k depending on your mood. I'm not a serious runner and started with the C25k a few years ago and that's what I generally do. I have to admit, I really enjoy going for a run when on holiday as it gives you a different view of the place.