Katy Perry‘s getting ready to take her fans through a series of lifetimes … ’cause she’s rehearsing for her upcoming tour — and, TMZ has exclusive video of the practice.

The singer-songwriter — who is set to embark on her “Lifetimes” Tour later this month — spent the first couple weeks of April rehearsing for the concert series … using an arena in Ontario, California to get ready.

We’re told Katy was very nice and professional with the staff who work at the arena … and, check out the clip for yourself — tons of futuristic lights and a huge infinity symbol literally taking center stage.

Worth noting … all these videos were taken before Katy went to space — when she revealed a setlist written on the back of a butterfly-shaped piece of paper to the camera.

Many online have been clowning Katy and the rest of the all-female Blue Origin flight for their trip to space … especially a moment after they touched back down to Earth when Katy literally got down on her knees and smooched the ground — after just 11 minutes in the air.