Hey I'm in year 13 as well. Do you know what topics you're stuck on or the types of questions you keep getting wrong? If you do that's great bc you have a starting point for revision. If you're not sure on content, prioritise that first and just keep going until you're confident on it.
If you feel that you know the content then it could just be exam technique or the way that your answers are written (this is something I struggle with a lot). What I'm doing now is looking at model answers on PMT and seeing how they are different from my answers. Most of the time your answers may not have the detail and specific subject terminology required or you've written the same thing but with extra waffle which can waste time. Once you know how to write the correct answers effectively, you can get extra time to use for checking your answers.
Regarding practicals, you can be asked to devise an experiment, explain how something works (e.g. recrystallisation), explaining how an experiment could be improved, explaining why there's a control group, etc. The control group questions are nice because the answer is always the same and it's to ensure that there are no other factors other than the independent variable affecting the experiment. However, you should practice the other types of practical questions as it can vary depending on the scenario.
If you'd like I can send you some practicals revision notes. If you don't mind me asking, what exam board do you do? I do OCR A.
All the best for A-Levels!!