Lemon juice is BAD for your skin, anyway. It's very acidic and will irritate your skin at the very least. It also makes you more sensitive to the sun so you're more likely to sunburn on the areas you use it, or develop sun-freckles or other damage, so it completely defeats it's supposed purpose.
The best way to get pale/lighter and stay that way is to avoid the sun. Number one rule. Don't want something to happen, don't do the thing that causes it. At all. Stay out of the sun, especially during the hours of about 10am to 2pm, when the sun is usually at it's harshest and brightest. If you're going to be exposed to it for more than 30 minutes at a time, either keep your skin covered, shaded, or wear sunblock with at least SPF 30-45 and reapply as the bottle instructs.
As for your current needs, exfoliate the areas you want to lighten. This will help you scrub off the burn and damaged skin layers faster and allow the undamaged and lighter ones to come up faster. This can be anything from commercially available products to just gently scrubbing with a soft wash cloth and body wash.