If your client base is large companies, all of which have professional purchasing departments, you will never get your rate back. Rate hike discussions are zero-sum negotiations in which either you continue working at your original rate or the purchaser takes a job performance hit. It may be easier to acquire new customers at a higher rate than it will be to jack the rate up on an existing customer. And eventually, you're going to run across clients you really want, under competitive RFP situations, where they'll demand "most favored" rates --- so that 60% "entry" rate is now your permanent negotiating floor, no matter where your industry goes.
Discount with project scope, or with deliverable depth, or with long-term support, or with scheduling flexibility. Some of these non-financial perks are more valuable to your clients than the monopoly money they're spending out of IT budget --- all the more reason not to send an "amateur" signal with a below-market rate. Don't discount with rate if you can possibly avoid it.