I don't think I've ever had a crepe myrtle that DIDN'T come back in spring without the tips of branches being bare. I think the tips just die off in the winter naturally. In fact, my father always told me to expressly cut off 1/4 the length of ALL branches (on younger crepes) BEFORE they releaf, to bring about 2-3 branches (and blooms) where there was just one before. This approach will have your tree blooming more and more each year. I have a baby Catawba down at our rural cabin (just 2' tall) and I already did this the first year, resulting in double the blooms and branches this year. Will continue to do this each February as is my practice. I have done this with all my crepes since my father's advice and people do comment on how prolifically my crepes bloom. Many people NEVER prune crepe myrtles, but it has been my experience with friends' crepes, if you don't prune a bit off the branches annually, the trees just get taller and taller, but bloom less and less over time.