When business is slow, it's easy to think clients have moved to cheaper products or decided to do without the services you offer. Particularly during such times, it's a good idea to survey present and recently departed customers in order to check the pulse of your business.
You'll probably discover some clients didn't like the level of service you provide. That's not pleasant to hear, but complaints of any kind are good. They give you a starting point for improvement.
Many former and present clients are nice people who don't want to complain. These are the people you need to talk to. Studies reported by the CornerStone Leadership Institute show that for every person who registers a complaint, there are a couple of dozen who don't say anything about it at all. This is why one might want to reconsider accepting "No news is good news," as a measure of client satisfaction.
Conversations with clients will show that you really care about them. They will be more loyal to you in the future.