Responding in a sweet manner when your boyfriend says "hi babe" is a lovely way to show affection and reciprocate the warm greeting. Here are some sweet and endearing responses you can use:
"Hi love! How's your day going so far?"
"Hey there, handsome! I've missed you."
"Hello, my sweetest! You always know how to brighten my day."
"Hi there, my darling! Can't wait to see you later."
"Hi babe! Sending you a virtual hug and kiss right back."
"Hi lovebug! Thinking of you always makes me smile."
"Hey, my one and only! What's on your mind today?"
"Hi sweetheart! You're the best part of my day."
"Hello, my amazing man! I hope your day is as wonderful as you are."
"Hi babe! You're the light of my life."
Remember, the key is to be genuine and let your affection and feelings for him shine through in your response. Tailor your reply to your unique relationship and use words that feel natural to you both. Sweet and sincere words will make him feel cherished and appreciated.