Yep, you definitely can. I improved mine significantly: 665 to 752.5. I did it basically by preparing this year, and last year I didn't.
If you did a lot of prep before, it might be more difficult, but as you say - if your techniques for practising weren't very good, thats what you need to sort out. It is supposed to be an aptitude test, so while you can practise the questions, and get used to the style, you can't magically make yourself more observant for AR, or better at maths, or better at comprehension without a LOT of work. It depends what you feel let you down - are you just not that good at it? Or did you not know how to approach the questions? Were you reading too slowly for VR?
It is definitely possible to improve your score, but it is a matter of working out what you can improve and acting on it.