Insha Allah, I am going for haj this year next week. i had difficulty of night emission in weeks intervals. it is very difficult during the haj, especially in Mina and Muzdalifa, to have a bath in the night or early in the morning, some time it may result in losing Subih prayer.
1. Is there any alternative for taking bath to be cleaned from Janaba?
2. Is it permissible to use innerwear if one afraid of Urine spreading in ihram dress.

Praise be to Allah, the Lord of the Worlds; and may His blessings and peace be upon our Prophet Muhammad and upon all his Family and Companions.

If a person ejaculates during the night or day he has to take a ceremonial bath.  Imams Ahmad, Ibn Majah and Al Tirmizi reported from Ali who said: 'I used to excrete Madhi, so I asked the Prophet (Sallallahu Alaihi wa Sallam) about it.  The Prophet (Sallallahu Alaihi wa Sallam) said: "Madhi (pres-seminal fluid) needs the Wudu and Mani (semen) needs the bath." 

Furthermore, it is forbidden to delay taking the bath until the time of a prayer ends.  If a person is confirmed that using water will harm him, or he strongly believes that it could increase in his disease, in this case it is permissible for him to make Tayammum (dry ablution) for the prayers, Tawaaf, etc.  Allah Says (interpretation of meaning): {…And if you are ill, or on a journey, or one of you comes after answering the call of nature, or you have been in contact with women (by sexual relations) and you find no water, perform Tayammum with clean earth and rub therewith your faces and hands (Tayammum)….}[4:43].

However, Tayammum is permitted only if one does not find the sources or means that make him able to use water such as using the hot water or drying or warming oneself just after the bath to avoid the cold, etc.

If he is not able to use water by no means then he may make Tayammum.

If any impurity such as the urine and the like fall on Ihram the prayers and Tawaf is not valid unless one cleans it or changes the Ihram.  Know that Ihram should be washed only by water, i.e. should not use soap or the like.

If a person is in the state of Ihram and cannot prevent the impurities except using a stitched underwear then it is permissible for him but he has to pay the expiation for the violation of one of the condition of Ihram.

Imam Al Nawawi said: If one needs to cover his head or to wear stitched clothes for some reasons such as to keep away from cold or hot in this case he has to pay the expiation.   Allah Says (interpretation of meaning): {…And whosoever of you is ill or has an ailment in his scalp (necessitating shaving), he must pay a Fidyah (ransom)…}[2:196].

If the semen falls on the clothes, it is not compulsory to wash it out since semen is pure according to the preponderant opinion of Muslim scholars.

Allah knows best.