A different times the following seem to have helped me:
a. Slow down, give it your total "A game" (I feel that this can be a little difficult sometimes online, due to the sheer number of tourneys u can play - with alot of distractions)
b. Try freshening things up a bit - why not try HU/6 handed/ or another poker game altogether??
c. Go UP the stakes. Yes I did say UP. You may find it increases your concentration and kicks in your A game, but also the players at higher stakes may understand (interpret differently?) some of the moves u make - in comparison to lower level players. I actually find it easier playing $100 + tourneys than $10 stakes.
d. Take a break and play Live poker only for a period.