You might as well just take it if you feel you have adequately prepared. Maybe there are some crazy exceptions where someone's LSAT score changes dramatically, but at the end of the day the LSAT is basically an IQ test and you are going to get what you get.
Obviously, preparation is key, but it sounds like you have been studying for awhile and if 157 is what you got after putting significant time in that is probably roughly how you will do. A 157 will definetly get you into law school and if you want to be a lawyer then law school is a good place to be.
If you are set on going to an elite school and won't be satisfied then there might be other things to consider.
I compare Law School to Basketball in a lot of ways and 157 is a solid score like a 6'6 guy trying to make the NBA he might get a basketball scholarship maybe even be able to play in some minor league, but probably won't make the NBA. However, the guy would be making a living as a basketball player and if that is what the person loves they will be happy.
Just like if you get a 157 you can get into law school you will become a lawyer and get a job as an attorney. Probably won't be working big law or making 200k a year, but if you want to be a lawyer again you will be happy.