Check the article for keywords. There might be synonyms for your keyword that researchers use. There might be additional keywords that will help you to narrow the scope of your search. Keywords are usually found above or below the abstract. Redo your search with these new or additional keywords.
Look through the article's references. You should be able to find citations to older, relevant articles there.
Search for articles by the same author(s). The author has likely written other articles on the topic.
Search the same journal for more. If a journal has published one article on a topic, it's a good bet that they have published others.
If you have a couple of weeks to a couple of months before your project is due, consider signing up for a search alert or a table of contents alert. Many of the databases have them and you may be able to incorporate the latest research into your project!