SOLVED

I had to modify my Custom Index Creator as follows.

Now I have my custom index always updated.

Adriano

using Examine;
using Lucene.Net.Analysis.Standard;
using Lucene.Net.Util;
using System.Collections.Generic;
using Umbraco.Core.Logging;
using Umbraco.Core.Services;
using Umbraco.Examine;
using Umbraco.Web.Search;

namespace AF.Examine.Index.Tools.For.UmbracoV8.Creators
{
    public class AFMembersIndexCreator : UmbracoIndexesCreator
    {
        private readonly IProfilingLogger _profilingLogger;
        private readonly ILocalizationService _languageService;
        private readonly IPublicAccessService _publicAccessService;
        private readonly IMemberService _memberService;
        private readonly IUmbracoIndexConfig _iUmbracoIndexConfig;

        // Since Umbraco 8 has dependency injection out of the box, we can use it to inject
        // the different services that we need.
        public AFMembersIndexCreator(IProfilingLogger profilingLogger, 
                                        ILocalizationService languageService, 
                                        IPublicAccessService publicAccessService, 
                                        IMemberService memberService, 
                                        IUmbracoIndexConfig umbracoIndexConfig) : base(profilingLogger, languageService, publicAccessService, memberService, umbracoIndexConfig)
        {
            _profilingLogger = profilingLogger;
            _languageService = languageService;
            _publicAccessService = publicAccessService;
            _memberService = memberService;
            _iUmbracoIndexConfig = umbracoIndexConfig;
        }

        // Noticed that we return a collection of indexes? Technically you
        // can create multiple indexes in an indexCreator :) You can have a look at
        // UmbracoIndexesCreator.cs in the CMS core and see how the CMS does that.
        public override IEnumerable<IIndex> Create()
        {
            // create my AFMembersIndex definitions
            return new[] { CreateAFMembersIndex() };
        }

        private IIndex CreateAFMembersIndex()
        {
            var AFMembersIndex = new UmbracoMemberIndex(
                                                    "AFMembersIndex",
                                                    new FieldDefinitionCollection(
                                                        new FieldDefinition("memberId", FieldDefinitionTypes.FullText),
                                                        new FieldDefinition("memberNodeName", FieldDefinitionTypes.FullText),
                                                        new FieldDefinition("memberLoginName", FieldDefinitionTypes.FullText),
                                                        new FieldDefinition("memberEmail", FieldDefinitionTypes.FullText),
                                                        new FieldDefinition("memberName", FieldDefinitionTypes.FullText),
                                                        new FieldDefinition("memberSurname", FieldDefinitionTypes.FullText),
                                                        new FieldDefinition("memberIntTel", FieldDefinitionTypes.FullText),
                                                        new FieldDefinition("memberFax", FieldDefinitionTypes.FullText),
                                                        new FieldDefinition("memberCel", FieldDefinitionTypes.FullText)
                                                    ),
                                                    CreateFileSystemLuceneDirectory("AFMembersIndex"),
                                                    new StandardAnalyzer(Version.LUCENE_30),
                                                    ProfilingLogger,
                                                    UmbracoIndexConfig.GetMemberValueSetValidator());

            return AFMembersIndex;
        }
    }
}