I created a truce with the Illyrians that cost me 300. They are now demanding 425 with a countdown timer. How do I accept this? I'm in the diplo window and my only option is to declare war.joruneEDIT: Never mind, I missed the 'insufficient funds' portion and had to liquidate assets.
Use the timer to position your troops into a better position. They will regret their renegotiation when you storm through 3 of their cities. Then you can make peace again for cheaper.