Most companies who issue Umbrella policies do not carry the entire risk themselves. Instead, they have "Treaty Reinsurance" with one or more reinsurance carriers. A given company might only keep the first $500,000 or less of your $2,000,000 policy. The remainder is laid off in one or more layers to reach the agreed aggregate limit. More than one reinsurer might be involved especially in higher limits. Generally these treaties provide that over time, the re-insurer doesn't lose money. And, the treaties cover a number of years until they are renegotiated. Umbrella losses are rare, and just a few can distort results causing unwelcome swings in pricing as treaties renew and the re-insurer is made whole.
Because so few Umbrella policies are written compared to HO or Auto, it isn't an important line of business to your company. They probably don't really care if you renew or not. They have to have it available because better customers who own lots of stuff which they can insure want it available. Personal Insurance (as opposed to Business Insurance) is a tough business to be in. HO policies have been a big loser for the industry for 30 years. It is very regulated. They make most of their money on car insurance.......