Make the U.K., Russia and the Ottoman Empires offers that they can't refuse.
Rather than making war with Russia and tempting war on other fronts, make deals with them that make them happy.
Secure their support with trade deals that are unfairly favorable to them. Offer to take their prisoners and dissidents. Offer to squelch activists in the empire who dislike them. Offer to build rail lines that connect their capitols to your empire at your expense. Trade them your colonies abroad for their cooperation.
Imagine how the world would have changed if the Louisiana Purchase had sold French North America in the Mississippi basin at a discount to the Ottoman Turks or the Russians or Portugal, instead of the Americans.
Carefully manage local elites
Co-opt existing business leaders and aristocrats in a manner that allows them a bit of control of the dramatic rate of change brought about by joining your empire and assures them a prominent place in it. Meanwhile, put local elites who refuse to be co-opted in fear for their lives.
Secure the full blessing of the Church
Do what it takes to get the Church on your side.
Consolidate your military position
Rather than further expanding, expand the French mass army (one of the first in history) to other countries, raising citizen armies and training them in every country. Then deploy them in each case far from home where they will have no local allegiances. Resupply your troops during the lull with weapons and logistic supplies.
Devote resources to propaganda
Hire pitch men and artists and playwrights and musicians to tell the story of the miraculous enlightenment of your empire for everyone to hear everywhere all of the time.