Basil dies out as it is a tender annual. It just can not take any cold. So yes, you have to plant new ones each year. I have never had mine reside even if I messed up and forgot to cut off a seed head.
Really you should cut the forming seed heads and not let the plant flower as it affects the taste.
I start my Dill from seeds I bought each spring as I don't get much reseeding. In fact I need to start my Dill and Cilantro soon.
I started my Basil seedlings here inside right after I started my tomato seedlings. Wow, that Basil sure does grow slowly!!
