This is a classic case of the old adage, sleep, creep, leap. The first year, a plant sleeps – you see little growth, though it is growing roots underground. The second year, it creeps – you see some growth, but it’s limited, and you may see a bit of flowering. On its third season in the ground, it leaps – it has had enough time to establish a good root system so it is able to devote energy into flowering and growing, and that includes reblooming. Your plant just needs a little more time to get a root system in place so that it can start flowering well. That said, once established, the key to rebloom on reblooming shrubs like Sonic Bloom weigela is that the plant must put on as much new growth as possible after its spring bloom. The more new growth it puts on, the better its rebloom will be, so it’s a good idea to keep the plant watered, especially if the weather is hot and dry, and to fertilize at least once more after its spring bloom to give it a little boost.