AFAIK there's no need to discharge the batteries before charging. The whole "discharge before charging" thing applies to NiCd batteries, to break the "memory effect", and was about 10% real-world effects due to bad electronics design, and 90% myth.
If there is something that I don't know about discharging LiPo packs before charging them -- please don't tell that to the batteries I fly my 'lectric RC planes with! For years I've just taken them out of the plane after whatever length of flight I may have put on them, tossed them on the charger, and flown them again after I hear the little tune. I haven't had to buy a new battery pack for years.