hopefully won't be an issue until next year.
One can never be sure. They will supercede if they feel she needs replacing.
Now what does it depend on?
This could be whether you wish to buy in another queen.
That could be whether she is still doing the job.
And that could be whether you are prepared to put up with what you get from them.
Buying in. Expensive early in the season. Change at your choosing (subject to queen availability. Don't do it too late in the year in case of a misfire.
Artificial swarm and go for uniting later with new queen. A/S timing may be chosen for you if not done early in the season. Normally they will not swarm until matured drones are present in the colony, so rush it at your peril - not enough good drones on the wing could mean problems later in the year.
If she is ailing, or the colony slow to build up, too much chalk brood, poor laying pattern, too much drone brood (especially in worker cells!) or other problem, the sooner the better.
Colonies tend to over-winter better with a young queen, so your over-wintering risk will increase if you keep her until 2012.
What you don't really want (with just the one colony) is for your bees to decide to supercede very late in the year. But, even new queens can be superceded after only a very short time.
One last possible consideration; how many times has she been treated to an oxalic acid trickle?
My recommendation, of course, would be to increase to at least two colonies - two are so much more easily managed, without trauma, than one. Losing a queen (with two colonies) is not such a great problem, at any time of the year, compared to just a single colony. Even a small second colony in a polynuc might be some insurance.
Regards, RAB