There are a lot of different statistics regarding implant service life, and the lifespan varies depending on saline/silicone/round/teardrop/smooth/textured, etc.
I have found that round, smooth, saline filled implants last an average of 14 years. This is NOT absolute fact, just observation and from reading. Of course, some will last way longer, and I have seen some crap out after a few days or weeks, due to manufacturing defect. In any event, it is safe to say that if you are happy with the implants, and they are giving you no problem, then leave them in. There is no need to change them routinely, like you would do with the oil in your vehicle. If it ain't broke, don't fix it.
A secondary or revision breast augmentation is generally much less painful, and the recovery in general is easier than the original operation. The rippling may be due to the implant or the capsule, or a combination. If the capsule has scar tissue bands, these can be weakened or eliminated during surgery, and this may add some discomfort, but nothing compared to creating the pocket under the muscle.
Textured implants allow for tissue ingrowth and when they change shape or position due to changes in the body position, these can cause surface ripples due to the traction that the implant surfaces places on the breast surface through the ingrown tissue (traction ripple). To minimize chances of ripples again, I suggest a smooth surface, round shaped, silicone filled gel implant placed under the muscle. At this time, the pocket/capsule should be visually and manually checked to ensure that there are no bands or constrictions that could create ripples.
Your perceived loss of implant volume is unlikely (though unless you have complete deflation). It is more likely that you are losing some breast volume as a result of your life cycle. When you get your replacement implants, you may want to explore getting larger ones to make up for the loss of volume.
Hope this helps.
