Is it permissible to divide profits equally between partners from a sum that was previously determined monthly from usury, in order to avoid usury, and what is the ruling regarding the past months during which usury was dealt with out of ignorance?

Your question is unclear, but if our understanding is correct, which is that you entered into a Mudarabah (profit-sharing) agreement on a specific amount of money rather than a percentage of the profit, and you wish to correct the transaction by making it based on a percentage of the profit without withdrawing the capital, then correcting the transaction is done by concluding a new contract based on a known percentage of the profit. There is no requirement to withdraw the capital. As for the previous period, the Mudarabah therein was invalid, and according to the majority of scholars, all the profit belongs to the owners of the capital, and you are entitled to a reasonable wage (Ajrat al-Mithl) for your work.