Should I let my site die, or commit to its success?

I'm kind of stuck in no mans land with a site I threw together last summer. The site is about Facebook slot machine games.

I was playing those games regularly and developed a spreadsheet to tell me how much I should be betting. I shared some of my charts with a few people, who then wanted regular updates. That's when I decided to build the site. You can see the site here: Manofa

I threw some ads on the charts and put some affiliate ads on the site. I have since stopped playing the games, and stopped updating the charts (for various reasons)

I haven't made any real income from the ads. Even after months of not updating, the site still has a loyal following and I still get messages from people asking and begging me to update the charts.

I'm going to have to invest in some programming and design if I want to continue the project.

Do any of the experts think that this project is worth pursuing? Is there a better way to monetize the site? Will this work as a mobile app?

I have not done any marketing, other than create the site and create a Facebook profile. I have not done any SEO, linking or advertising. All traffic is organic. (see image for traffic stats)

To continue I will need to use dynamic SQL charts instead of .pdf. The site needs to be redone. Is it worth it, or should I put this to bed?

Thanks...