What should a girl do who suffers from the continuous dripping of urine for a long period after urinating, and the repeated emission of gas, which affects her ablution and prayers, and does the ruling on سلس (incontinence/ سلس البول) apply to her?

If the discharge of urine or gas is continuous, then your ruling is that of one afflicted with سلس (incontinence). You should perform ablution for each prayer after its time has begun, take precautions, and whatever is discharged will not harm you. However, if it stops at a known time sufficient for purification and prayer, then wait for that time. If you doubt whether something has been discharged, the default is that it has not, and you should not pay attention to doubts. You are not required to change your clothes; rather, wash whatever you are certain has been touched by impurity. It is permissible to adopt the Maliki school of thought, which does not necessitate purifying impurity in cases of extreme hardship or excessive doubt (waswasa).