Shorter method:

If one is unable to recite all these sooras, he should recite folowing
Tasbeehat-e-Arba’a 100 times;  Al Hamd 100 times, Sura Tawhid 100 times, Ayatul Kursi 10 times. Salawat 100 times.
THEN Sura Tawhid again 1000 times instead of the many surahs. Refrence
Shaikh Mufid has also mentioned similar method. Syed Tawoos in Iqbal Aamal has also mentioned (if in safar/ travel) 100 Time times Sura Tawhid instead of all surahs.
Rajab 15 Aamal
Normal method
Fast on 13 , 14 and 15th Rajab
On 15th Rajab
After the obligatory Zuhr-Asr Prayer is completed, face the Qiblah and recite the following surah multiple times as in the table below:

Number of Surah name of Surah  recite Times
1 Al Hamd 100 Time
112 Ikhlas 100 Time
Ayat al Kursi 10 Time
6 An’aam 1 Time
17 Bani Israel 1 Time
18 Kahf 1 Time
31 Luqman 1 Time
36 Yaseen 1 Time
37 Wassaffat 1 Time
41 Ha Mim Sajda 1 Time
42 Shoora 1 Time
44 Dukhan 1 Time
48 Fatah 1 Time
56 Waqea 1  Time
67 Mulk 1 Time
68 Al Qalam 1 Time
84 Inshiqaq 1 Time
85 Al Burooj 1 Time
86 ţ-Ţāriq 1 Time
87 Al-‘A`lá 1 Time
88 Al-Ghāshiyah 1 Time
89 Al-Fajr 1 Time
90 Al-Balad 1 Time
91 Ash-Shams 1 Time
92 Al-Layl 1 Time
93 Ađ-Đuĥaá 1 Time
94 Ash-Sharĥ 1 Time
95 At-Tīn 1 Time
96 Al-`Alaq 1 Time
97 Al-Qadr 1 Time
98 Al-Bayyinah 1 Time
99 Az-Zalzalah 1 Time
100 Al-`Ādiyāt 1 Time
101 Al-Qāri`ah 1 Time
102 At-Takāthur 1 Time
103 Al-`Aşr 1 Time
104 Al-Humazah 1 Time
105 Al-Fīl 1 Time
106 Quraysh 1 Time
107 Al-Mā`ūn 1 Time
108 Al-Kawthar 1 Time
109 Al-Kāfirūn 1 Time
110 An-Naşr 1 Time
111 Al-Masad 1 Time
112Al-‘Ikhlāş 1 Time
113Al-Falaq 1 Time
114 An-Nās 1 Time