That's where the rest of your mouth comes into play - a little nuzzling and smooches, nibble with the lips, suck a mouthful of pussy in and work it around, etc. About the time the tongue gives out she's probably at a point where one of these tricks will put her over the edge. And I count myself very fortunate if she's one who likes her legs together at climax, so I can feel the contractions ripple through her thighs as they clamp around my ears. (Of course, don't do it with a figure skater - have you ever noticed the legs on those girls? Going down on one is just asking for massive cranial fractures!)