Thr economic power loss depends on what was being lost, for instance, the French lost all but the Caribbean in the Seven Years War but didn't lose much economic power due to their continued possession of Sugar producing islands. A colony doesn't equal free money, and the North American lands were never as prosperous than the British Thirteen Colonies.

However, to pay for constant wars, the Crown would take loans to pay for the Wars. Before the Revolution, the Crown could only afford to pay the interest on the loans after paying for the mechanisms of State. Beyond this is tbe loss of economic potential due to distrupted trafe during the wars. While war at this time involved smaller numbers than the Napoleonic Wars, armies would disrupt trade by their existance in an area or navies would hire or pay privateers to disrupt naval trade.

I myself find trouble with understanding the logic of diplomacy at this time but you must remember that war at this time is about dynastic struggles with scientific wars meant to reduce bloodshed. The trading of lands is meant to invite peace for the lands that the victor wanted.