Answered by Sayyidi Habib Umar bin Hafiz (may Allah protect him and benefit us by him)
What can we recite to increase in reliance upon Allah (tawakkul)?
Recite the following seven times in the morning and evening:
حَسْبِيَ اللهُ لا إلهَ إلَّا هُوَ عَلَيْهِ تَوَكَّلْتُ وَهُوَ رَبُّ العَرْشِ العَظِيمِ
Hasbiy’Allahu la ilaha illa huwa `alayhi tawakkaltu wa huwa rabbu’l-`arshi’l-`azim
Allah is sufficient for me; there is no deity save He. On Him do I rely; He is the Lord of the Awesome Throne
Also repeat the following in abundance:
حَسْبُنَا اللهُ وَنِعْمَ الْوَكِيل
Hasbunallahu wa n`am al-wakil
Allah is enough for us and He is the best One in whom we place our trust.
رَبَّنا عَلَيْكَ تَوَكَّلْنا و إِلَيْكَ أَنَبْنا و إِلَيْكَ المَصِير
Rabbana `alayka tawakkalna wa ilayka anabna wa ilayka al-masir
Our Lord, in You we put our trust, to You we turn in repentance and to You is the final end.
The following will also be of assistance: remembering Allah in abundance with presence of heart, bestowing abundant prayers upon Prophet ﷺ reading the books of the pious and reflecting on the stories contained in the Qur’an.
 Sayyidi Habib Umar mentions in Khulasat al-Madad that this should be read 70 times in the morning and evening