check these links, and share your experience here once you have completed your return visa procedures.

http://www.qatarliving.com/visas-permits/posts/rebringing-family-after-6...
http://www.qatarliving.com/advice-help/posts/advise-return-visa

http://www.moi.gov.qa/site/english/departments/PassportDept/news/2011/01...

http://www.moi.gov.qa/site/english/departments/PassportDept/resources/20...

dont forget to share your personal experience once you have competed for you, because it will helps others..thanks & all the best.