Do you continue having high aso levels from having scarlet fever or will they go back down to normal?

Maybe: Aso (antistreptolysin o) is an antibody response to the infection. It is common after strep. Many times the level does not return to negative or "normal" but they will decrease to a normal range. It is helpful to have a measurable antibody response. It indicates the immune system is working well. We want them in a range that indicates healthy response and not an overactive response.

ASO levels...: ...Rise with any exposure to group a strep, even if no symptoms appear, so for some people they never go back to "normal" - but, otoh, except for people with rheumatic fever, they are of no concern at all - in fact, looking for evidence of rheumatic fever is pretty much the only reason to ever measure aso levels.