We haven't gotten munch Kindle traffic on this forum and none of the posts address your specific .sol question. So I'm sorry to tell you that there is no known saved games hack where you could substitute something like a ".sol" file on your Kindle Fire device and then continue the game at the level PAST the space invaders game.
There is always the chance that someone will notice this topic and chime in with the sort of fix you're looking for but in the meantime I'll quote myself from a
similar question posted by an Android player that also had trouble getting past the Space Invaders:
You'll just have to use the tried and true method of taking out most of the descending 'invaders' but leaving just a few of the top-most ones alive so that you can repeatedly hit the "mother ships" that pass overhead until you're forced to finally take out the last straggler invaders. As you know, the 'mother ships' are worth more points than the little buggers so you just might be able to get enough points to take you over 1000 if you concentrate on them.Good luck, kindle 63! And please post a follow up to let us know how things eventually turn out.