Before you rebirth
Claim every ready collection reward in the Encyclopedia. Then open the skill tree and identify an upgrade you can afford. The Demo only enables the rebirth action when you have enough Rebirth Coins for an available node.
What resets
The active run starts over: normal run progress and regular chest-item stacks marked for reset return to their starting state. This is why the collection rewards need to be claimed first.
What persists
Skill-tree progress is permanent across the rebirth. Lucky Coffee is also marked not to reset, so the one-time roulette reward remains part of your save.
What to do next
Return to the main loop and use the new permanent node to reach the next collection goals faster. The full release has a larger tree, so treat this table as Demo 1.1 data.