"repent and ask for forgiveness and make dua' that Allah make things better"
your belief in that Allah and that HE (swt) can make things better - must be stronger for it to actually effect you which will lead you to seeing things in a optimistic perspective. You should be able to have blinding trust in the will of Allah and the very act of repentance and seeking forgiveness is Dhikr, i.e. the remembrance of Allah when done wholeheartedly should also help you feel better and remove your fears and anxieties, this is a sign of a true believer. Also we all know of the beatiful Ayah in Surah Ar-R'ad Ayah number 28, where Allah SWT says, "Verily in the remembrance of Allah do hearts find satisfaction."
when thoughtfully contemplating over the problems which are causing you to feel fear and anxiety, evaluate the situation and try to possibly resolve it through practical means, as this way you know you've given it your best to make sure you don't lose whatever you fear losing. Otherwise, if you can't do anything AT ALL, then yes Du'a and turning to Allah are your only solutions, keep your heart and tongue occupied in reciting Qur'an, Dhikr or even attending talks/events to engage your mind in things that will benefit you rather than harm or hurt you.
but yeh as I said, depends on the situation, if you don't want to lose this thing then fight for it through legit means, oh and make sure the thing you don't want to lose is halaal/legit for you in itself.
wa Allahu Alam.