Lipo cell has a max voltage of 4.2v/cell. You can check cell voltage thru balance tap so you'll know what it is. Mine come off charger at 4.185v. They will stay at that voltage level for about 10days, then slowly lose voltage.

You def do not peak a lipo - asking for a damaged lipo batt that way. charge only using a lipo protocol - CC/CV. If you charge it before race and its been charged previously and not run, it will revert almost immediately to the constant voltage part of charge routine which usually takes a while to complete.

Less expensive lipos may lose voltage faster, I don't know. If you have a decent DVM, you can see exactly what your cell voltage is and know what you could gain by charging again. I think you'd have more to gain by looking into lipo heater or warmer - that seems to have more potential for performance gains than toppoing off for 10-15mv.