To aid you in keeping coverage at an adequate level, some companies offer an "Inflation Guard Endorsement." This endorsement will allow your insurance company to automatically change your policy limit during the policy period. Normally, the higher premium is not paid until the time of renewal.
Even if you have this endorsement on your policy, you should check your coverage limits periodically to make sure you are adequately, but not excessively, insured. Not all companies offer this endorsement, so check with your producer or company if you are interested in purchasing it.