You can currently go back and grind the wave before a boss. If you are on a boss wave, click the wave icon at the top of the screen for the wave before the boss and it will take you to that wave (there will be an infinity sign in the background that tells you you've gone back a wave). You will stay on this wave until you manually take yourself back to the Boss by clicking on the icon on the top of the screen for the boss wave.
...Day 1,000,000... I can't stop this endless path of destruction and despair. Floor 100,000 is still suffering, Bobby and Natalia are dead. Amenhotep is still waiting for my Ascension choice. My 10,000 ancient is finally collected, along with 100 relics. Cid is at level 1,000,000.
 "Time Clickers"){kind=icon}
 "Clicker Heroes"){kind=icon}
You can currently go back and grind the wave before a boss. If you are on a boss wave, click the wave icon at the top of the screen for the wave before the boss and it will take you to that wave (there will be an infinity sign in the background that tells you you've gone back a wave). You will stay on this wave until you manually take yourself back to the Boss by clicking on the icon on the top of the screen for the boss wave.