Well, they will probably have you read from the sides for the role you fit now. You may not play the same role at 39-years-old as you did at 17-years-old. And most community theatre auditions have "sides" from the scenes they want you to read for.
Of course, yes, prepare by reading the entire script again!!! Great idea and rehearse different roles you fit now, as you're old enough to play the Mom, and not necessarily the young teenage girl.
Most of the time, you won't be asked to do a monologue for community theatre. They will, 90% of the time, just ask you to read a side or two.
If you are asked to do a monologue, take a role like Mrs. Gibbs or Mrs. Webb and take out the other person's lines; just react to them; and do about a 1 to 2-minutes monologue on that. You can prepare one, just in case.
Enjoy! Congratulations, I think it's really cool you want to do it and I send you good vibes! Community theatre is so much fun!