Basically you have 3 choices.

Archive and condense.

Go to the Enterprise version, which has much greater list limits.

Or, Start a new company file using the lists of active customers, vendors and employees, put in the balances and move forward in the new file.

The easiest route would be to go with Enterprise, since it will update the data from your existing file. But it is more expensive, and is an annual subscription that you must maintain.