Is the repentance of someone who paid a bribe to obtain a travel visa accepted, given that their Islam has currently improved, and are their good deeds performed in that country accepted? What are the conditions for repentance in this case?

Traveling to non-Muslim countries is permissible provided that one is safe from temptation and able to openly practice religious rituals. If the travel in question falls into this category, then purchasing its visa is permissible, and there is no harm in paying a bribe to obtain it if it does not cause harm to others. If the situation is not as described, then one must repent. If one is residing in non-Muslim countries without the aforementioned condition, then one must return to Muslim countries. If one paid money as a bribe without necessity, then one must repent by regretting it and resolving not to repeat it. Their good deeds are accepted if they are sincerely for Allah and in accordance with His law.