A trick to writing fresh content on a consistent basis month in and month out is to learn to look at your topic from all angles and all levels. This is beneficial for your readers, because you are creating a library of information that covers your topic inside and out. This is also beneficial SEO_wise, because you are systematically creating a collection of resources that covers your subject backwards and forwards. This creates a greater chance of your article turning up for searches on every aspect of your niche. Last but not least__learning to cover your topic from all angles and all levels of depth is beneficial for YOU, because it forces you to establish your expertise in your field. If you are not already an expert in your field when you start writing articles, you surely will be after a year of consistently writing articles on every conceivable angle of your topic each month.
This approach tends to work better for articles that are jam packed with information and/or those that take a broad, aerial view of the topic, but it can also work with articles that are a close up view of one specific topic. For example, I've written many articles on how to create an effective resource box, and from that one very laser beamed topic I have branched off articles on extremely specific elements of that already specific topic. I assure you, no matter what your article is about, you can write about it more in depth in a new article.