cow boy cactus

[herbie]

Sorry if anyone has read this in the home section i didint see gardening bit when i posted it but here goes again.
I bought 3 cowboy cacti roughly 6 months ago,2 was for freinds and theres havent changed in apperance at all we all live near each other and all are on window ledges i direct sunlight but mine is going crazy and producing new shoots almost weekly even the new shoots have shoots someone told me to repot them or the original will die is this right?? also its in a 8ins pot shall i put it in a larger one and if so how big but if i do that it cant stay were it so obviously likes it.Thanks in advance for any advice