You could use Timer1(or 3) configured as a counter and count the external 1Hz pulses. This way you could count pulses for up to six days without waking the pic. If you configure the counter with a prescaler 1:8 and preset it with 11536(65536-54000) you will count 8*54000=432000secs, that's exactly 5 days. When you have had this interrupt 73 times, exactly one year(365days) have passed.

/Ingvar