It isnt necessarily that you need to lag it up. I think you my just be missing the oppertunity to limp some marginal stuff like 87 etc in lp in either limped pots or raised pots. Recently ive had a lot of success playing cards opposite to what i think my opponent has and therefore hamering him/her when they miss flops or i hit a big one.
Stealing these pots is what has bulit me stacks in mtts and won me more pots playing NL. I still generaly play a tightish game unless its shorthanded but it may be you need to play more connectors and siilar hands hen given opperyunity in raised pots than actually having to lag it up