It is always important to shop around for insurance as premiums between companies will differ and you won’t know unless you take a look! Generally, companies with loyal customers rely on the fact that you are happy with them and so are unlikely to check how competitive your renewal premium is (which is often higher than it was the last year and more than competitor premiums)
Before calling your existing insurance company to discuss their renewal premiums, it is worth looking on a comparison site to identify comparative policies and the cost of these so that you have a benchmark which you may have as bargaining power