there are various ways of communication.of course the best would
be a face-to-face conversation with her,but ur in army now..
phone talks and emails to update her on ur current status should
suffice.send pictures of urself when u bookout the next
time.account to her ur army life and how ur adapting to it...if
possible,the occasional army happenings u experience during
trainings.
of course,u should inquire abt her current affairs too.make jokes
that u'll make up to her when u come out of army to humour
her.
most imptly,tell her that u love her.u too miss her as much as she
does.
this should keep the relationship ongoing,if she understands ur
agony as well. 
