I don't know what IE stands for but if it means that you were working on the speech delay with an expert then it must have worked. Lots of kids can catch up from a delay with the right guidance and practice.
My son grew out of his speech delay last school year. He's been in speech therapy since he was 2 and around Jan/Feb of this year, he graduated out of speech therapy. They said he reached all of his goals except for the ones that he shouldn't need to develop until he is 8 years old.
It might be that now it's more on the average side, Some kids can improve very easily, Others take a while even a couple of years, If you think your child is talking more, and putting sentice together now, then he/she might be fine now.
Both of my oldest kids, are on theraphy for that, My daughter (4) is going for her second year of theraphy, and my son (3) is going for his fist year now.
I think it's definitely possible to get better with the right help.
My son started working with First Steps when he was 2, he started preschool when he was 3. He's 4 now and is getting caught up quite nicely. He's still a little bit behind, but more than likely he'll be right on track by the time he starts kindergarten.