Be happy you had such great conversions before.
Im normally around 1:3k and im 1:3300 this month so a bit higher but last month was actually 1:3600 so im seeing an improvement and slowly getting back to "normal".
I send an assload of traffic though so my higher ratios still do very well.
I wouldnt get too panicked as mentioned ebb and flow. Just keep your head down and work hard and develop some new traffic sources to go along with your current setup.
ps. Ive had some record high and record low days all in the same week! So dont get too awfully bothered. ;)