It looks like you would benefit from a more comprehensive ongoing marketing campaign.  Three tactics that I suggest are incorporating direct mail, one-to-one prospecting, and e-mail.

Let's start with direct mail.  Begin by identifying your best prospects by business type and any other important criteria.  Then contact a list broker to rent direct mail lists of individuals by title in the business categories that fit your criteria and are within your geographic market area.  Rent your lists for a minimum of two or possibly three mailings, then create a direct mail campaign with a benefit-oriented theme to send to this group.

The typical contact sequence in business-to-business marketing is call-mail-call.  That means you need to develop your own in-house prospect list (in addition to your larger direct-mail lists that you will rent) that includes at least several dozen prospects.  Contact them first by telephone, then follow up by mail, in person or via e-mail.  Construct a database of these prospects and the leads that are generated by direct mail and gain permission to e-mail to this in-house list.  On average, it takes eight or more contacts with prospects before sales are closed, so if you're not touching your prospects at least once a month, you're missing out on opportunities to grow your business.  E-mail is a fast and a virtually free way of maintaining contact with your in-house database.  Combine that with additional direct mail, phone calls, meetings and other sales tactics for a winning combination.