That's a hard one to answer. IQ scores can change over the course of many years or even within a year or so or they may not change much at all. It depends on the kid and other factors.
The main thing I'd want to know in your situation is why the school wants to retest her. Do they retest everyone every few years to requalify for GT services or do they have specific concerns with her perfomance not being on par with what they'd expect given her prior IQ scores?
If it is the later, I'd be more concerned about her losing services she currently has and think about whether any twice exceptionality issues or long-term underplacement educationally is likely to be impacting her performance. Can you test privately or do you need to do it through the school and how high would her scores need to be when retested to not lose GT services? I really hate high stakes tests -- 'make this one number or you're out' type of things. Are you looking @ a situation like that here?
