I would understand 'regardless of how the kiss goes' as as 'no matter how 'successful' or 'unsuccessful' the kiss turns out'. In other words, 'how WELL the kiss goes'. This probably refers to the responsiveness of the partner. If she kisses you back and appears enthusiastic, you should keep on holding her - and even if she doesn't, you should still maintain the contact for a few moments. It makes sense. A gentle hand around a waist, arms or shoulders is a sign of affection. Whether the kiss turns out to be lengthy, warm and passionate, or brief, cool and platonic, you shouldn't break off all contact the moment the kiss ends. Whatever kind of kiss you've shared, breaking off all physical contact at the end of a kiss seems abrupt and cold. Spend a few moments enjoying some gentle hand to body contact, as well as some eye-to-eye contact and a smile. If anything, this stage is more important than the kiss itself!

Hi, The sentence means, whatever happens during the kiss -if it is a short one, long one, shallow one, deep one- keep your hands on her body, do not let her go. Regardless means: whatever the circumstances. I hope this helps! Aleks