First, congrats on #2. :)
I had a girl, then a boy less than 3 years later. One of my co-workers surprised me with a diaper shower. It was simple appetizers, cupcakes, and each person came with 1 pack of diapers, and I also got some boy outfits! Unless your children are going to be more than 5 years apart, having a baby shower isn't appropriate. There are other ways to celebrate a new baby than to go as far as a shower. Did you keep your crib, swing, infant care seat, stroller? In my "circle", it's frowned upon,- registering for any child other than your very first, is a no no .If it's your family that wants to purchase big things, why register? If you need girl clothes, you should try a luncheon with the intent to receive some clothes or personal items. You might also consider a Meet & Greet for the baby once she arrives, and of course you'll get gifts! Mostly clothes! That could be an "open house" for people to stop in through the day.