Praise be to Allaah.
Allaah says (interpretation of the meaning):
" and [Allaah] has not laid upon you in religion any hardship" [al-Hajj 22:78] and
" Allaah intends for you ease, and He does not want to make things
difficult for you" [al-Baqarah 2:185].
It is sufficient, my sister, if you perform wudoo' before every prayer after the time for it has begun, and do not worry about anything that comes out after that. You could also put a piece of cloth or something similar so that the najaasah (impure substance - in this case urine) does not spread, then throw it away and wash yourself before making wudoo'. We ask Allaah to heal you and give good health to you and to every sick Muslim.