Can a repeated phrase be changed in a dementia patient?

This is a simple brain glitch that may or may not change, but there is nothing you can do to change it.

My dad did this when he was in the advanced stages of cancer and his cognitive abilities declined dramatically.
Once, when he was lucid, I asked him why he kept asking for help. He said he didn't know, but we determined that he was comfortable and pain free.
It was destressing to hear him, but it felt easier knowing that he was okay. I hope this helps you to cope, too.

I knew a lady who kept saying “Help. Help.” She had plenty of help and wanted for nothing. She didn’t talk much other than that, and it went on for a couple of years as I recall.

My mom’s phrase is “ it’s broken”. OMG..Everything is broken. Nothing stops that loop!

My Aunt had dementia for 12 years before she passed. At one point she went through that phase, saying that exact thing. That's when we started her on anxiety meds it eventually stopped. She was probably trying to communicate something to us, but for some reason couldn't. Then she went on to shadowing and yelling her sister's name continusously till it nearly drove everyone insane. She never completely stopped yelling her name but it diminished over time. When she passed she could talk (mostly nonsense) and answer simple questions. But she definitely needed the meds.

No, she will eventually move onto another phase, her brain is broken, it is a continuous loop, round & round we go!

You probably can not change her phrase loop.
You might be able to find something that she can do that might keep her occupied so that she does not say "help me"
Does she like music? Can you put on songs she will sing to?

My Husband did not have a phrase he made noise and moaned.
Sometimes quietly other times very loudly.
I dealt with it by telling myself that I would miss it when he was gone.
I do..... sometimes.

there are medications that might help but medications with Parkinson's can be tricky.

Quite honestly...no. Now it may change after a while to another phrase, but once something gets stuck in a broken brain it's next to impossible to get it out.
I would just give family and friends a heads up about what she's saying and to just try and ignore it as she doesn't really need help.

No you cannot. Realize it's the dementia talking, and causing the loop thinking. Make sure there's nothing she needs....that she's not hungry or thirsty or needing a brief change, not in pain or needs to be repositioned, etc so you're sure she doesn't need help before you dismiss her plea, though. Oftentimes the patient is unable to articulate what it is they do need.