If the pack is balanced [you do balance charge I hope] and not puffed, keep using it.
Charge at 1C of rated capacity, unless, after a few cycles, it's apparent that you're down a significant amount of capacity, in which case, charge at 1C of observed capacity.
ALWAYS use an LVC on your speed control, and remember, if your LVC is set at 3.2V or higher, you're not going to see a 100% capacity charge, which is fine.
If you're really concerned, Lipo sack, temp probe, and something fireproof to set up on [concrete patio, driveway, etc, something out of the house] could be called for, and NEVER charge unattended, even batteries you don't have concerns about.
Privateer racing lots of stuff.
Remember kids, racing isn't fair!