You can repost jobs and or give the current job a new ID number occasionally. This will “trick” the job board into thinking it is a new job and move it closer to the top. I don’t recommend doing this more than once every 2 or 3 months. If you do this frequently, Indeed has the right to remove the job posting. Here is some information that might be helpful on this…http://blog.indeed.com/2013/05/28/search-quality-doing-whats-best-for-job-seekers/
To give the job a new ID number click the Jobs tab -> Name of the job -> Edit Job -> Change the ID number -> Save. Then you should also re launch the job. Click the Launch tab -> Edit Launch Status -> Check the boxes of where you would like to post the job -> Next -> Verify the posting location -> Next -> Submit.
Another option would be to create a few new jobs with different titles.