I am often left in open-mouthed astonishment when watching matches as players will return short backspin serves the same way, with simple long pushes to the opponent's backhand, over and Over and OVER!!! There is little attempt to vary these returns or do much of anything to mess up the server. And yet they seem surprised that the server is ready for these simple pushes, usually with a big third-ball loop attack. If the opponent serves and pushes, then perhaps pushing the serve back long over and over will work. But that's mostly at the lower levels. If you want to reach the higher levels, you have to do a bit more with the receive.
If the serve is long, it's a bit more simple - just loop the serve, forehand or backhand. If you don't loop, at least play aggressive, since a passive return of a deep serve is easy for the server to attack, since he has more time then off a short serve. (Aggressive usually means a topspin return, i.e. a drive or loop, but it can also be an aggressive push.) The same is true of a short sidespin or topspin serve (which is somewhat rare at the lower levels) - you should flip it.
However, against a short backspin serve, you can't loop, and flips are a little trickier. But you have more options to mess up the server, if you only use them. So what should you do against a short backspin serve? There are three main possibilities, but with countless variations.
Never forget that your purpose in returning a serve is to mess up your opponent. You don't do this by being predictable with passive returns; you do this with unpredictable and effective returns.