Summarize the following:
If you haven’t heard from your friend in a while, give them a call or send them an email. Keep your tone casual, and don’t mention that you’re unhappy with the friendship. Just tell them that you miss them, and ask if they want to spend time together soon.  You can say something like, “Hey, Anna! I haven’t heard from you in a while, and I was hoping we could catch up sometime. Are you interested in getting lunch together this week?” If the person turns you down, wait a week or two and try one more time before you assume they aren’t interested. No matter how much time has separated the two of you, it can be easy to fall back into old friendship patterns when you do something you once enjoyed. Consider this an opportunity to knock out two birds with one stone, per se. Reconnect with your old pal and rediscover an old past-time. Perhaps you and your old friend grew up near a stable. You can say, "Hey, it's been years since I've gone horseback riding. Why don't you join me?" A challenge is also a great way to strengthen an existing bond. Learning a new skill or hobby can help the two of you get closer. Reach out to your friend and suggest a new activity that you think you both would enjoy.  For example, if both of you are relatively adventurous, you might ask, "I heard about a trail in the area that was just renovated. Want to go for a hike on Saturday?" This activity can also offer the two of you a chance to talk and/or sort out your differences. Your friend might want to hang out in a different environment or do a different activity than you're used to. Be open to their suggestions, and try out their ideas. If you're nervous about you and this person reconnecting, others can offer a great buffer. Invite several mutual friends over to your house for a game night, or out to an event in your town. Use the group activity to chat your acquaintance and remind them how much fun you can be. A group activity lowers the pressure that can be present in a one-on-one interaction. This is a smart route to take if you're unsure about why the person is losing interest in you. You can tease out information without any unnecessary tension. Don’t complain to your friend or start calling them more often to make up for their lack of contact. This behavior will annoy them, and they will probably start avoiding you even more.  Don’t jump to conclusions. Your friend may just be busy. Act normal and see if the situation clears itself up. It will probably take several attempts and conversations before you can restore your friendship. Keep reaching out to them occasionally, but give them the time and space that they need. When you’re around the person, act friendly and cheerful. Don’t be passive-aggressive, even if you’re feeling miffed about their lack of contact. Tell them you’re glad to see them, but don’t act like your happiness depends on their attention. You may want to think of a few topics to discuss ahead of time. This will help the conversation flow naturally. For example, you might discuss new hobbies, summer plans, favorite TV shows, or family news.

Summary:
Get in touch with the person. Invite them to engage in a favorite shared activity. Offer to try something new together. Plan a group activity. Avoid nagging or acting clingy. Be pleasant and upbeat.