Maybe talk about any new challenges faced at school?
I found this on reddit, give it a read
"I got waitlisted last year too, so I totally know what you’re going through.
First though - you should breeeaaathheeee. College admissions can be pretty stressful, so it’s a good idea to take step back (smoke some pot lol) and relax.
Now that you’ve done that (actually do try to relax), let’s talk about the essay + grades:
For the grades they ask for in the first section - make sure you stay on top of them. The committee might forgive you for an A to a B+, but falling to a C in any of your classes, in my eyes, would vastly lower your chances. Keep those grades up!
tldr: Senioritis is ok, but not too much.
For the essay, treat it like an update for the admissions committee. It’s an invitation to tell them all you’ve been up to this year, be it in the classroom, on the field, or any other place your extracurriculars might take you. Here’s where it’s really important to “be yourself”; you want to let your voice shine to the point where it truly feels like I’m talking to you. If you’re passionate about something recent you’ve been doing - let them know.
The above part of your essay should be like 250-350 words, so make sure you prioritize the important stuff. In the next part of your essay, give 'em what they want.
Above all admissions committees want qualified students, that truly want to go to their school. So you, being the qualified waitlisted student that you are, give 'em just that.
If there are specific academic interests/extracurriculars you want to continue at Cal (ex. Blockchain) reach out to the organizations for those interests (ex. Blockchain @ Berkeley) and get involved by asking for info/attending workshops etc. Afterwards, simply write about your experience in the essay. Actually reaching out, and getting involved with the community, through actions, speaks waaaayy louder than anything you can say. So get involved."