If you left legally then there is nothing stopping you from applying again. You will probably have to explain why you left and why you feel this time you can complete your program.
They are more concerned that you will leave once your studies is over, assuming that you are not getting PR or a Work permit.
There could be a concern that you may not be able to handle the program, but you have shown that you have earlier done the sensible thing and returned. It might be slightly more difficult but not impossible.