A marketing plan is used to reach a target market with a specific message. As time goes by and the marketplace changes, your company's structure and approach must change as well, reflecting the new realities in your area of business. In order to keep your marketing plan effective, you need to evaluate your advertising programs at least once a quarter to keep them up to date.

Product

As you review your marketing plan, you need to evaluate the product or service you are marketing, according to the marketing experts on the VPI Strategies website. Determine if the features of your product are still relevant to the marketplace. Examine sales figures to see if the product is gaining or losing popularity. Project sales over the coming fiscal year to see if the company will be able to see a return on investment from the product sales.

Message

Evaluate whether or not the message in your marketing plan is effective. Study the demographics of the geographical areas where you place your advertising and see if sales are more improved there than in areas where you are not doing a significant amount of marketing. You may be using the wrong medium for your message. Examine your target audience to see where they find their information. Your initial marketing research may have indicated that the target audience relied primarily on television for their information, but subsequent information may reveal that the Internet is a more effective medium.

Objectives

A marketing plan is measured on how well it reaches its objectives, according to economist Charles R. Hall, writing on the Texas A&M University Department of Horticultural Sciences website. Determine whether or not the plan is staying within its budget, is reaching the target audience and is moving product. Define a comprehensive set of metrics that you can use to track the marketing objectives, then evaluate actual performance against those objectives to determine if any changes need to be made.

Networking

Your marketing plan can help create future opportunities for your company by inspiring others to talk about your product, according to marketing expert Stuart Ayling on the Website Marketing Plan website. One of the ways that a marketing plan helps your company is to motivate retailers and customers to publicly recommend your product. If your marketing is not creating an industry stir, then ask customers and retailers what is missing. Once you have an understanding of why your marketing plan is not causing a network of retailers and customers to speak about your product, you can make changes that will start to spawn word of mouth advertising.