I'm not going to forgive some of my daughter's debt that she owes me
Why does she owe you money?
When she was young she has wanted to go to school overseas. Instead, I sorted out her tuition fee.
She needs to learn some responsibility and that's a good lesson to teach. You shouldn't feel too bad about it.
I hope she won't ask me for help in the future.
If you stipulated it was a loan, then she needs to comply with the terms: what is owed should be paid. I think it's OK to gently keep reminding her about this.