Every renewal, you need to review your business insurance to ensure it is fit for purpose. Items like turnover, salaries and gross profit can all affect your insurance in terms of price, but also validity of cover (i.e. if the information is incorrect, an insurer may refuse to honour a claim or pay a significantly reduced amount).
The business description also needs to be carefully considered, plus stock levels, plant sums insured and much, much more.
Any decent Commercial Insurance Broker will always personally visit you, at least 6 weeks prior to renewal, and assist in a full review. However, many Brokers have minimum premium levels before they are happy to commit this amount of face to face service with clients (sometimes more than £10,000 per annum) so always ensure you are aware of the service you will receive when selecting a Broker.