Probably another letter, perhaps with the same result...Unfortunately these things can bounce around between solicitors almost ad infinitum or until one party gets fed up & files an initiating application...
So.. Why not just consider making an initiating application yourself now & save a lot of money & angst... the filing fee is $350....
Initiating Application Kit (do it yourself kit) - Federal Circuit Court of Australia
Your solicitor will want a deposit into a trust fund of thousands, & charge you at the rate of around $400-450 an hour
When the application is filed, he will be served & will be COMPELLED to respond, the you can actually start to mediate & reach a settlement.