No worries
We release property every week and I do a blog post about each one, probably 2-5 properties each week then smash it out via social media (facebook, twitter, linkedin, etc). This seems to work quite nicely, though I only have to sell it once to be fair.
After this, we will also email the property out (with new content from that week), this gives that page a massive boost in traffic, which definitely slows down the process of dropping off the rankings, in my opinion.
So perhaps do a weekly email about new products and include some relative content in the email as well (as Matt said, link to the products in the content too!)
Doing this I have been steadily climbing up the rankings for my main keyword, last week I went up 15 ranks according to SEOmoz Pro! (It’s been about a month or two since I started doing this).
I think my main problem is that the site has a lot of old pages. Also the main pages need a bit of on-page optimization, so this may be something to look at as well J