I'd say this at this point as well.‘Hey I’ve noticed you haven’t replied is everything okay? I really need the money as it’s taken me into my overdraft and I’m being charged daily for it. Do you want me to call round for it?’
I've had a friend do the same and iirc the amount was £70 and I really didn't have it to spare; I only lent it because she promised to return it in 4 days (payday).
She didn't pay for over a month and as I texted once a week to ask, it turned out that she was telling our mutual friends how disappointed she was in me because I was making such a fuss about a small amount of money, and that a 'true' friend wouldn't blow something like that out of proportion the way I was. In her head, I was being a drama queen and I had ruined the vibe of our friendship by asking her to return it because it meant that I didn't trust her to do it on her own. Oh and that she wasn't answering my messages out of principle because she felt I was treating her as though she isn't trustworthy.
When in reality, I was really short on cash at the time and I really needed *my* money back, and she wasn't replying so I was stuck not knowing what to do.
It not only ended our friendship, but I ended up removing several of our mutual friends from my circle because they said I shouldn't have overreacted! It still upsets me to think about it.
Anyway, perhaps add on to the line quoted above: I wouldn't normally keep asking but I'm now overdrawn and being charged.... and your silence is confusing me. Is everything okay at your end? Something along those lines to let her know you're not trying to nag but are confused...that approach may get her to reply.
Edit: I think it's better to ring her up rather than text, since she keeps ignoring the texts. And if she doesn't answer, then you can send a follow up text saying you're concerned/is something wrong?