Well i dont really repeat. Most of my stuttering is in the form of blocking as well, often silent. I sometimes prolongate but thats when im actually trying to stutter out the word. Blocks are bad man, it's like a sign that we're so scared or uncomfortable or whatever with stuttering that we cant allow ourselves to do it. I wish I had a trick for you but tricks dont work. I usually just try to ease into the word from the start and keep moving forward, trying not to get too hung up on the tough sound. Then after i say it i might repeat it if i didnt think they heard me clearly.