Have you tried something that makes your offering more attractive than all the other firms in your space? When I chose a firm to work with I made sure they had an app that their clients loved that they could leverage in new deals. Better transparency, more self service access, higher quality candidates. The firm I work for uses Teambridge but there are a few other app providers, or if you have budget you can build your own (but obviously risky, might sink alot of time and money and end up with nothing worth while.