Couple of things to keep in mind. Initial messages sync will by default sync 5 (expendable to 14) days or up to 200 (expendable to 750) messages whichever condition is met first. So if she receives 500 messages a day then only 200 will be synced to bb or half of the day and not 5 days.
In order to get these 5 days or 200 messages after re-activation, you'd need to remove her account from bes and click yes to delete bb information from user mailbox. Wait until user is gone from User pending delete tab, re-add him/her back to a bes and assign password and policy. Wipe handheld and re-activate.