I planted my Clematis about 2 months (or more) ago and it has not grown even 1 new leaf, even though it looks very healthy. It did have a couple of flowers and 1 bud which flowered. I believe that the rootball might still be intact even though I loosened it before planting. Should I wait and dig it up this fall, loosen the roots, add more soil and replant? Or is there something else wrong and what should I do? Thank you.
As long as it looks healthy and it's planted in an adequate location with well-draining soil, I would not dig it back up. The roots need time to become established and this will only cause the plant more stress. You may instead try giving the plant some fertilizer to boost its growth. Use a fertilizer high in phosphorous on your clematis. Something that is about a 10-20-10 NPK ratio or even rose food can be used to fertilize clematis. Anything having too much nitrogen will only result in an abundance of foliage growth with few blooms. Here is more information on growing clematis vines: https://www.gardeningknowhow.com/ornamental/vines/clematis/growing-clematis.htm