got valid study visa but cannot go to canada.. plz guide

[umair81]

SALAM TO All

I got admission for MSc Internetworking in UOA for fall 2010.
applied for visa on july 20th.
got  18 months multiple entry visa on 20th of august..

my question is

due to so family problems i cannnot proceed this fall to canada. and neither can deffer to next term.

if i do apply for the same programm next year and get admitted will i have to reapply for the visa. or can use the current issued visa as it will still be valid for next 8 months after next september.