You can just start posting again. You don't need to do anything. If I where you though I would update all the info, make sure it is in the right category, make sure any links still work. Delete some old posts if they are not relevant. Make several posts. schedule them to go out one day after the other. Give it a week of posts and you should see some activity, not a lot but you will have breathed life into it again. When people come to a page they will see the date of the posts as recent and that will help. You could also pin a new post to the top. You could even invite the members to get in touch with you with questions or requests.
What niche is the page in?
I would love to know how you progress with it. I have over 200 pages in the exact same situation, some older than yours, some with more fans. All are just sitting there right now. If you find a way that works well please feel free to PM me, I would love to hear of any success you had.