Jpa with hibernate implementation does not generate tables in postgresql

Good night to all I'm using Jpa with hibernate implementation for among other features generate tables, the problem is that from one time to another the tables stopped being generated, someone else has gone through this

Follow my persistence.xml

<?xml version="1.0" encoding="UTF-8"?>
<persistence version="2.0"
xmlns="http://java.sun.com/xml/ns/persistence" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://java.sun.com/xml/ns/persistence http://java.sun.com/xml/ns/persistence/persistence_2_0.xsd">
<persistence-unit name="comunicaVisual"
    transaction-type="RESOURCE_LOCAL">
    <!-- meu provider é o hibernate -->
    <provider>org.hibernate.ejb.HibernatePersistence</provider>
    <!-- mapeamento das entidades criadas -->
    <class>br.com.drem.entity.Pessoa</class>
    <class>br.com.drem.entity.Cidade</class>
    <class>br.com.drem.entity.Estado</class>
    <class>br.com.drem.entity.Pais</class>
    <class>br.com.drem.entity.PessoaFisica</class>
    <class>br.com.drem.entity.PessoaJuridica</class>
    <class>br.com.drem.entity.Usuario</class>
    <class>br.com.drem.entity.Funcionario</class>
    <class>br.com.drem.entity.Venda</class>
    <class>br.com.drem.entity.Produto</class>
    <class>br.com.drem.entity.Contato</class>

    <!-- se determinada entidade não estiver participando da query ela vai ser excluida do trabalho -->
    <exclude-unlisted-classes>true</exclude-unlisted-classes> 

    <properties>
        <!-- postgres é o nome da minha database -->
        <property name="javax.persistence.jdbc.url" value="jdbc:postgresql://localhost/postgres" />

        <!-- drive do postgresql 9 -->
        <property name="javax.persistence.jdbc.driver" value="org.postgresql.Driver" />

        <!-- ususário da base de dados -->
        <property name="javax.persistence.jdbc.user" value="postgres" />

        <!-- Senha -->
        <property name="javax.persistence.jdbc.password" value="1" />

        <!-- nome do schema-->
        <property name="hibernate.default_schema" value="dremcom_drem" />

        <!-- metodo para criacao, atualizacao ou exclusao de tables -->
        <property name="hibernate.hbm2ddl.auto" value="update" />

        <!-- para visualizarmos as querys no console -->
        <property name="hibernate.show_sql" value="true" />

        <!-- para formatamos as querys -->
        <property name="hibernate.format_sql" value="true" />

        <!-- dialeto do banco de dados -->
        <property name="hibernate.dialect" value="org.hibernate.dialect.PostgreSQLDialect" />


        <property name="hibernate.cache.use_second_level_cache" value="true"/>

        <!--  -->
        <property name="hibernate.cache.use_query_cache" value="true" />
        <property name="hibernate.cache.region.factory_class"
            value="org.hibernate.cache.ehcache.EhCacheRegionFactory" />

    </properties>
</persistence-unit>