My little lemon tree has had a hard winter (though not as hard as my calamondin which nearly died and is not yet out of danger...) but is now full of little buds. It's still inside, under a bathroom window which gets good sunlight through frosted glass. It's still in the plastic pot it came in. Should I, can I, repot it now? At all?

It also has some kind of infestation which I can't see - the leaves have brown streaks on them a bit like very broad leaf miner marks, and there is a lot of sticky honeydew on the tree, but I can't see any bugs. The bathroom has also been home to overwintering harlequin ladybirds, and I shall be very cross if this turns out to be some kind of aphid - those ladybirds ought to have dealt with it! Any ideas?