It depends on what the root cause of the problem is. If you are losing reception due to some intermittent interference, then a new AirPort Extreme may not solve your problem. If you are in the same room with line-of-sight between your AirPort and a wifi client like a laptop or iOS device connected to your wireless network, do you still see them problem? If it only occurs when the microwve oven, some other appliance, or a cordless telephone is used then the problem may not be with your AirPort Extreme. I'd urge you to try and find the source of the problem before going out an buying a new AirPort Extreme, when you may not have to.
1) If the reception comes and goes as a result of wireless interference from other sources in your home and around the home...other wireless networks in the neighborhood....or...nearby cordless phones.....then a new router is likely to experience the same issues. See this Apple support document for symptoms and fixes of wireless interference.
2) If the reception comes and goes as a result of an aging power supply in the older AirPort Exteme or another component that is intermittently acting up, then a new router should take care of that.
What we cannot tell you is whether 1) or 2) applies to your situation. If possible, it would be good idea to take the older AirPort to an Apple Store or Apple Servicer....if you have one near you....to let them take a look.