Is it permissible to deposit additional money into an existing prohibited trade based on usury, with the aim of recovering the original capital, without the intention of profiting, and based on His saying, the Almighty: "And if you repent, then you shall have your principal sums"?

Since you have become aware of the prohibition of the trade you invested in, due to its reliance on usury, you must cease it immediately and withdraw your principal. It is not permissible for you to remain in it or increase your capital under the pretext of compensation. The Islamic Fiqh Academy has issued a resolution stating that it is not permissible to purchase shares of usurious companies with prior knowledge of their nature, and that it is obligatory to exit them immediately upon discovering the usurious nature after purchase.