I can't argue about the apps - I was told I would be better off spending money for someone to brand an app for me then to pursue more internet marketing - there may be truth in that - I wish I would have thought it through as that was about 5 years ago.
If you're talking about a branded MOBILE app for yourself (don't know if that's what you mean), you could use realtordotcom's Collaborate app. But, you'd have to have generated some leads to invite them to use it. I say this because if your website isn't generating a whole lot of leads, if traffic is down... Well, you know, it's a vicious cycle.
Then again, if you've only got ONE website, you might think about creating a few more that target particular segments of your market (niches). (If you've not already done this). After all, there's only so many keywords that one website can effectively promote. One website can't be all things for one market anymore IMO.