Yes, play in some higher level rooms, and no, you won't lose a level. If the players are higher level and killed you, then you won't lose any level. If you do well against them, you will gain a level. It's like this, if a lower level person has killed you couple of times, you will lose a level. However, if you keep getting killed by higher level people, it's not worth it to play any further as it may mess up your online stat (K/D and W/L ratios).