The lower-risk version, if the direct one feels like too much for the two big ones: raise the rate for new clients immediately and let the existing ones follow at a natural boundary.
A natural boundary is the start of a new project, a contract renewal, a new financial year, or a change in scope. At that point the conversation is not I am putting my prices up, it is here is the quote for this piece of work — which is a completely ordinary sentence.
What this gets you:
- A rate you can say out loud without flinching, which matters because you will be quoting it to strangers within a week
- Evidence. Once two new clients have accepted the higher rate, telling the older ones is much easier, because you now know the number is real rather than hoped for
- Time to build the pipeline you said you do not have
The cost is that it is slower, and there is a trap: the gap between what new clients pay and what your oldest and best clients pay grows quietly until it is embarrassing, and the longer it goes on the harder that conversation gets. So set yourself a date — you will bring everyone onto the new rate by such-and-such — rather than letting it drift.
The common ending to the drift version is realising you are charging your two most important clients the least of anybody, which is roughly where you are now after four years.