I had this problem with my dog. She used to be really good at recall as a puppy but on long walks she would not get recalled properly - only so we could see her.
She then associated this "recall" with coming and finding us but running off again. She now knows two commands - recall to be put on the lead and recall to be seen.
I found the best way to train recall again was before a walk. Click the lead clip and recall your dog using a command, make them sit by you and clip on their lead + treat and praise. Then the ultimate treat - a walk!

So basically just be careful when recalling your dog, make sure every time you do it correctly and praise for it.

Hope this helps!.