After spending some time I solved the second and just noticed the solution for ALL OTHER LEVELS are THE SAME as Lv.1 !
Which is still:

↑↑←← ↓→↓← ↑→↑→ ↓↓←↑ →↑←← ↓↓→→ ↑←↑← ↓→↓← ↑↑→→
UULL DRDL URUR DDLU RULL DDRR ULUL DRDL UURR




This solves ALL LEVELS.

To get the achievement, you do not need to do Lv.1 for 10 times. You can actually FINISH this game.

Hope this helps a little.
Thanks