How do i fix a blanket i made 4 years ago?

I crocheted a blanket for my step son about 4 years ago. It was the first blanket i ever made and now it is starting to come apart where i tied the yarn strands together. Is there a way i can fix it without completely taking it apart and remaking it? He loves is blanket and really wants to have it back. any advice is greatly appreciated. Thank you.