Leaving/re-entering just before visa expiry

[Spark]

My girlfriend is a Japanese on a student Visa which is due for renewal at the end of October. We have been invited for a weekend in Dublin to joint celebrate my birthday and the birthday of one of my friends in the same period and were just wondering if my girlfriend would be OK to leave/re-enter on her current Visa and then send it to the passport office for processing as soon as we get back.

Thanks.