I have this problem of constant gas. I read online that if you have this then you do one wudu per prayer. But sometimes really late at night it can go away. I am not sure specifically what time it goes away. It is just on random days like today. The thing is I have already read Isha, so if it goes away at night then do I have to repray Isha?
First off, you need to be aware that there is no such thing in Islam as redoing your prayer because your released gas later on. The moment you finish your prayer, you can release gas or anything else that negates the ablution (wudu).
You only redo the prayer if you released gas DURING the actual prayer.
As far as releasing gas throughout the day, that's either how your body functions or your diet is heavy on spicy, gassy drinks, etc.
I sincerely hope this makes sense. Do comment if you need more clarification.
Allah (SWT) knows best.
وَجَاهِدُوا فِي اللَّهِ حَقَّ جِهَادِهِ هُوَ اجْتَبَاكُمْ وَمَا جَعَلَ عَلَيْكُمْ فِي الدِّينِ مِنْ حَرَجٍ مِلَّةَ أَبِيكُمْ إِبْرَاهِيمَ هُوَ سَمَّاكُمُ الْمُسْلِمِينَ مِنْ قَبْلُ وَفِي هَذَا لِيَكُونَ الرَّسُولُ شَهِيدًا عَلَيْكُمْ وَتَكُونُوا شُهَدَاءَ عَلَى النَّاسِ فَأَقِيمُوا الصَّلاةَ وَآتُوا الزَّكَاةَ وَاعْتَصِمُوا بِاللَّهِ هُوَ مَوْلاكُمْ فَنِعْمَ الْمَوْلَى وَنِعْمَ النَّصِيرُ (الحج:78)
This AYA tells us that whatever we are doing as a muslim, if it is difficult for us, we are doing it wrong.
Especially for As-Salat as it is the way to find peace and happiness in our hearts.
The Prophet Muhammad (SAWW) says before doing it
أرحنا بها يا بلال"make us comfortable with it (As-Salat)"
To conclude, repeating salat at night causes you trouble then you must not repeat it.
Note that the Satan wants you to repeat your salat to make it a burden for you, so that you hate your religion. You should not obey him and be patient.
لَا يُكَلِّفُ اللَّهُ نَفْسًا إِلَّا وُسْعَهَا
ALLAH does not burden a soul beyond that it can bear… (Qur’an, 2:286).
You have to pray to ALLAH as HE wants and HE wants us not to have troubles practicing Islam. We should obey HIM.
Do your ablution (wudhu) for each salat and do not worry about anything until InshALLAH you're blessed with good health and your sickness goes away.
And remember: do not give heed to Satan's whispers.
First of all, you have to know the reason for the constant gas, maybe it is related to the type of food you eat, simply visit a doctor and inshallah you will be fine.
Secondly, you need to have wudu just before the prayer, once you finished your prayer, you can do whatever you want as long as it is Halal