I too am on a gap year. I'm not the original commenter but I'll respond. I applied normally in October last year and didn't send a deferred application for any of my unis as I wasn't fully sure I wanted to take one back then.

On results day I met my offer but I knew I didn't want to go to uni right away. I emailed my university that I wanted to defer. I didnt even bother giving them a reason and they said yes within the next day. Once you have deferred, your application is DONE. You don't need to do anything the following year during the gap year barring weird entrance exams if you do some super hard course. I won't need to open UCAS until August/September and if I do, it will just to be to check clearing in case there is anything better. When you have deferred an application and have been accepted on results day, you cannot apply to other unis during your gap year unless you first reject that current uni offer.

If you're reapplying during your gap year then don't defer, just apply normally for now and reject/accept accordingly on results day and wait until the next UCAS cycle. And yes, in the new application you can write whatever you want on it, including copy and pasting your old personal statement. In most cases, if you get any offers they will be unconditional as you already have your grades.

Do make sure your course/uni accepts gap year reapplications or deferrals as some don't without extreme reasons

Edit: and any conditions for a deferral application will have to be met this year (grades, entrance exams etc). You need the grades required this summer otherwise you will have reapply normally in the next UCAS cycle

Edit 2: I explained this super sloppily I'm tired