Sure! Here are the rewritten sentences:

1. Are you interested in hanging out with friends at weekends?
**Do you fancy hanging out with friends on weekends?**

2. Duong was very busy; however, he spent the whole day at the Lim festival.
**Duong was very busy, but he spent the whole day at the Lim festival.**

3. The buses run every 15 minutes. The trains run every 30 minutes.
**The buses run every 15 minutes, while the trains run every 30 minutes.**

4. Mai has many stamps, for she likes collecting stamps.
**Mai likes collecting stamps, so she has many stamps.**

5. I get up earlier than I did last year.
**Last year I got up later than I do now.**