I like For( loops better - they were made to do this kind of thing.
However, a For( loop works a little different from Repeat, so the time will be different.
Get a real stopwatch and start this program at the same time you start the stopwatch. At any time (the longer the better accuracy), stop your stopwatch and press any button but [On] on your calculator. Write down both the number shown on the calculator and the time on your stopwatch. Then press [On] to quit the program.
Divide the number from your stopwatch by the number your calculator output. That's about how many seconds it takes for it to loop.
Repeat the process many times, and find the average of all of them. Then go back to the code I gave you and replace the last argument 1 in the For( with that average. When you run your program again, it should loop about once every second.
By the way, for my 83+, it was .041322314