Bone you're fine replacing the spring straightaway. Of course, carefully clean and lube your LCP per the manual before shooting. If you're not 100% on the 13lb spring, keep an eye on this pack:
http://www.midwayusa.com/product/757441
BTW ignore the included firing pin spring. But do be careful to pair the inside and outside recoil springs properly. And make sure the widened end of the spring goes front. This is SO annoying if you forget it
Repeating myself here, but the Hogue grip is at LEAST as important as the spring, IMO.