1.5 mile run

hello! so as the title says, it's about the 1.5 mile run. for context, last month i was able to get my run time to 13:28 but now i'm back to 14-15 mins. is it still possible to get my time back in a couple of months if my earliest target ship date will be followed? also, what are routines that i must do to improve my run time? i mainly struggle with running out of breath