Nordstrand also make some soapbars, but I'm not sure if they'll be the right dimmensions for you.
You could always keep the preamp and just have it so it's possible to bypass? Do you leave the cable plugged into your bass when you aren't playing it, as that would keep draining the battery. I generally only change batteries every 6 months, other than with my first active bass, that I had left plugged in when I first got it

.
The only reason I bring up the preamp part is because, to me, it would make more sense to just change one thing or the other. You might find that you get the tones you like just by changing the pickups.