Replying to "good to hear from you" can be done in a warm and positive manner. Here are some possible responses:
"Thank you! It's great to be in touch again."
"Likewise! I've been meaning to catch up with you."
"Thanks! I was just thinking about you too."
"I feel the same way! It's been a while since we last spoke."
"I'm glad you reached out! How have you been?"
"It's always a pleasure to hear from you!"
"I agree! Let's not wait so long next time to get in touch."
"Thank you for reaching out! Your message brightened my day."
"I was just about to get in touch with you too! How's everything going?"
"Good to hear from you as well! What's new in your world?"
Remember, the key is to reciprocate the positive sentiment and express your appreciation for the contact while opening up the conversation for further communication and updates.