Don't say:
She's lived here since two years

Say:
She's lived here for two years.

Note:
For is often omitted We can Say: I've been here for two years or I've been here two years. Place the preposition for before words or phrases denoting a period of time: for three days, for six weeks, for two years, for a few minutes, for a long time. Use it with any tense except the present.