can i improve now?

im in 12th ,preboards are going rn..and im gonna write jan attempt ,i got a 21/300 in my last mock(full portion).i didnt study anything so i got very low marks..i made a lotm of mistakes in [physics.in](http://physics.in) maths i wrote only 3 questions,all 3 of them were right. i want to improve my score..ik 12th syllabus pretty well and some 11th.i mainly face issues in organic chemistry,11th physics and maths..can i improve at least in april or even in jan if possible..or is there no hope... my school is also keeping exams..what should i do