First, clarify exactly what realtors mean by "value." Often they base their assessment on what apartments in your building are actually selling for right now - which isn't quite the same as an objective market price. If your apartment is just sitting on the market and not selling, then yes, you need to lower your asking price. But if we're talking about a theoretical revaluation, it might just be a tool to get you to work with that particular agency.
As for protecting your interests: if you're not planning to sell anytime soon, you shouldn't obsess over the current valuation at all. Real estate moves slower than the stock market, and seasonal fluctuations, local changes in the neighborhood, or just a dip in demand during a particular period - that's all normal. Your apartment is still an apartment, its functionality hasn't changed, utilities work the same way.
If you do decide to sell down the road, then yes, you'll need to account for current market realities. But there's no rush - selling at a loss after a year of ownership often just means you won't find a buyer willing to overpay for the urgency. It might be useful to periodically check listings for neighboring apartments to get a sense of the actual price level, rather than just listening to people who make their living on commissions.