Reincarnation is a mechanic in the chao garden pet simulator seen throughout the Sonic series, whereby a chao that dies can be reborn as a baby.1
'Reincarnation' is the name given to a form of bioligcal antisenescence present in chao and some chao hybrids. Those that are reborn in this way almost always lose all conscious memories of their previous 'instance', usually irrecoverably; however they may retain muscle memory and other subconscious instincts.